Zickar v MGH Plastic Industries Pty Limited (1996)

(HCA, 14 November 1996)

Toohey, McHugh and Gummow JJ [maj.]

Kirby J [sim.]

Brennan CJ, Dawson and Gaudron JJ [min]

REASONS FOR JUDGMENT

BRENNAN CJ, DAWSON AND GAUDRON JJ. [Minority Judgment]

The appellant was 21 years old when, on 15 October 1987, he collapsed at work. A cerebral aneurism had ruptured. It resulted in severe brain damage. The appellant has made some recovery, but it is unlikely that he will return to work. The aneurism was a congenital weakness.

The appellant made a claim for compensation under the Workers Compensation Act 1987 (NSW) ("the 1987 Act"). In the Compensation Court of New South Wales, Judge Thompson held that an injury occurred in the appellant's brain when the aneurism ruptured and that the rupture was not a disease. Judge Thompson awarded compensation without deciding whether there was any causal relationship between the appellant's employment and the rupture. He made no finding as to whether stress experienced in the appellant's employment played any part in producing the rupture. It was sufficient that it occurred while the appellant was at work. On appeal by the respondent, MGH Plastic Industries Pty Ltd, the New South Wales Court of Appeal by majority (Meagher and Powell JJA, Priestley JA dissenting) allowed the appeal. The issue that now falls for determination is whether the appellant's claim for compensation depends on proof of the elements contained in par (a) of the definition of "injury" in s 4 of the 1987 Act or proof of the elements contained in par (b)(ii). Section 4 reads as follows:

In this Act -

“injury” -

(a) means personal injury arising out of or in the course of employment;

(b) includes -

(i) a disease which is contracted by a worker in the course of employment and to which the employment was a contributing factor; and

(ii) the aggravation, acceleration, exacerbation or deterioration of any disease, where the employment was a contributing factor to the aggravation, acceleration, exacerbation or deterioration; and

(c) does not include (except in the case of a worker employed in or about a mine to which the Coal Mines Regulation Act 1982 applies) a dust disease, as defined by the Workers' Compensation (Dust Diseases) Act 1942, or the aggravation, acceleration, exacerbation or deterioration of a dust disease, as so defined."

Judge Thompson awarded compensation on the footing that the rupture was an injury as defined in par (a) of s 4; the Court of Appeal remitted the proceedings to the Compensation Court to determine whether the claim satisfied the requirement of par (b)(ii).

The definition of "injury" or the context in which the term appears in the various State, Commonwealth and English laws has not been uniform and, from time to time, the various definitions have been amended. In the citation of Australian or English authorities on the interpretation of the term "injury" in statutes relating to workers' compensation, it is necessary to refer to the text which the court was expounding.

The English Workmen's Compensation Acts of 1897 and 1906 each imposed liability on an employer to pay compensation if "personal injury by accident arising out of and in the

course of the employment is caused to a workman"[1]. In the provision contained in those statutes, a causal relationship between the injury and the worker's employment was imported. The term "personal injury" was not expanded by any reference to disease or to the consequences of disease. In Fenton v Thorley& Co, Limited Lord Macnaghten said[2]:

"Now the expression 'injury by accident' seems to me to be a compound expression. The words 'by accident' are, I think, introduced parenthetically as it were to qualify the word 'injury,' confining it to a certain class of injuries, and excluding other classes, as, for instance, injuries by disease or injuries self-inflicted by design."

His Lordship approved [3] a decision in Stewart v Wilsons and Clyde Coal Co, Limited in which Lord M'Laren observed[4]:

"if a workman in the reasonable performance of his duties sustains a physiological injury as the result of the work he is engaged in, I consider that this is accidental injury in the sense of the statute."

Fenton was followed by the House of Lords in Clover, Clayton & Co, Limited v Hughes [5] where "personal injury by accident" was held to cover a rupture of an aneurism brought on by straining to tighten a nut. Lord Loreburn LC posited this test [6]:

"In each case the arbitrator ought to consider whether in substance, as far as he can judge on such a matter, the accident came from the disease alone, so that whatever the man had been doing it would probably have come all the same, or whether the employment contributed to it."

Under the English Acts, the consequence of the progress of a disease did not constitute "personal injury by accident" unless some event that occurred in the course of the employment contributed to the consequence. The cases drew a distinction between injuries to which employment has contributed and injuries which are solely a consequence of a progressive disease. That distinction has permeated later statutory formulations of the definition of "injury" and judgments interpreting the various formulations.

TheCommonwealth Employees' Compensation Act 1930-1956 (Cth) ("the Commonwealth Act") contained a provision imposing liability similar to that contained in the English Acts, but the Commonwealth Act expanded the basis of liability. The word "or" was substituted for "and" [7] so that the Commonwealth was liable to pay compensation if "personal injury by accident arising out of or in the course of his employment ... is caused to an employee". In construing the Commonwealth Act, this Court followed the decisions of the House of Lords: The Commonwealth v Ockenden [8]. In that case, as a consequence of rheumatic fever, a naval serviceman while on naval service developed incompetency of the aortic valve and aortic regurgitation. His condition developed "in the course of his employment". Nevertheless, his claim for compensation failed. The Court (Dixon CJ, Fullagar and Taylor JJ) denied [9] that earlier authority suggested "that a sudden physiological change produced by the inevitable course of a progressive disease and in no way related to any incident of [the worker's] employment" could amount to an accidental injury in the course of employment. The Court, speaking of cases where liability depends on "injury by accident [arising] in the course of the worker's employment" said [10]:

"In such cases the traditional view must still prevail that a physiological change, sudden or otherwise, is not an injury by accident arising in the course of the employment unless it is associated with some incident of the employment. Indeed to hold otherwise would be to strip the word 'accident' of all meaning by treating as such any distinct physiological change which is nothing more than the sole and inevitable result of the ravages of a disease. Such changes, even if they can be called accidents, occur not in the course of the employment, but, it may, perhaps be said, in the course of the disease."

The serviceman's claim failed.

Ockenden was distinguished in Kavanagh v The Commonwealth [11]. In that case, the worker vomited while at work and the vomiting ruptured his oesophagus. His death

supervened on the rupture. There were two issues in the case: was the rupture an "injury by accident" and did it arise "in the course of employment"? The Court was unanimous in holding that the rupture was a "personal injury by accident" although there was no external cause [12]. Dixon CJ, speaking of the rupture of the oesophagus, said [13]:

"It is a sudden destruction of tissue by force or pressure. It is true that the force or pressure was not exerted from without the body, but that I think makes no difference nor does it make any difference if it occurred, as it may have done, as a consequence of another organ of the body, namely the stomach, responding to a virus infection".

In reference to the passage last cited from Ockenden [14], his Honour said [15]:

"It would not appear to me to be correct in point of law to apply the passage to such a case as the present where you have what is clearly enough an injury by accident though not occasioned by any external force or agency. I say this because I do not think that it is consistent with s 9(1) as it now stands to deny that an event or state of affairs which in truth amounts to an injury by accident did not arise in the course of the employment because its occurrence cannot be attributed to or associated with the 'employment', including in that word the nature of the employment, its incidents and all that the employee may do or refrain from doing in pursuance or in consequence thereof."

Fullagar J held [16] that the English cases above cited established that the rupture of the oesophagus was a "personal injury by accident". He said of changes resulting solely from disease [17]:

"The true position in such cases is that compensation cannot, in the absence of some special provisions ... be recovered unless the 'physiological change' was associated with some episode or incident in the worker's employment - such as lifting a heavy weight or hurrying up a steep slope. It is therefore literally true to say that, in the absence of any such episode or incident, the worker fails to establish 'personal injury by accident arising in the course of his employment'. But the real truth in such a case is expressed not by saying that the worker has suffered personal injury by accident outside the course of his employment, but by saying that the worker has not suffered personal injury by accident at all."

A minority of the Court (Taylor J [18] and Windeyer J [19]) would have denied recovery to the worker on the ground that no incident in his employment contributed to the rupture. But the majority held [20] it to be sufficient that the rupture occurred in the course of the worker's employment. All judgments distinguished the facts of that case - the onset of vomiting followed by the rupture - from the case where the relevant event was "nothing more than the sole and inevitable result of the ravages of a disease". Windeyer J said [21]:

"It was quite unlike an episode that is an ordinary consequence of the progress of a disease, such as we have had to consider in other cases. It was not an accident arising out of the deceased's employment; but the Commonwealth Employees' Compensation Act, like some other Australian workers' compensation statutes, is satisfied when injury by accident arises either out of or in the course of the employment."

The worker's claim succeeded in Kavanagh but, in The Commonwealth v Hornsby [22], delivered on the same day as the judgment in Kavanagh, a stroke due to a thrombus forming in an atheromatous cerebral vessel was held not to be an "injury by accident" but the natural progression of an autogenous disease [23]. The worker's claim failed.

In that case, Fullagar J discussed three classes of cases which fall for consideration when the phrase "injury by accident" provides an element of a worker's right to compensation. He said [24]:

"In the first place, there are the cases in which a disease has been actually contracted through exposure to infection or other risk attendant on the conditions of employment. It has been said that the entry of a harmful bacillus constitutes an injury by accident. ... Then there are, secondly, the cases where there is actual

internal physical injury such as the rupture of an aneurism or of an oesophagus (Clover, Clayton & Co Ltd v Hughes; Kavanagh v The Commonwealth). It has been said, naturally enough, that the breaking of an artery cannot be distinguished from the breaking of a leg. Then we have finally the class of case in which death or incapacity results not from an actual physical injury, external or internal, but from the development or culmination of a pre-existing and progressive morbid physical condition. In these cases the final occurrence which results in death or incapacity is commonly referred to as a 'sudden physiological change'."

His Honour observed [25]:

" Cases belonging to the second of the three classes mentioned above are not properly regarded as cases of disease at all. They are cases of injury within the ordinary acceptation of that word, and, where the employer contested liability, it was usually on the ground that there was a pre-disposing physical condition and that it was not enough that some incident of the employment had contributed to the death or disablement. To this the answer of the courts was, in effect, that the employer must take the worker as he finds him. This is now well settled."

In the context of Ockenden, Kavanagh and his Honour's citation of Clover Clayton, this observation relates only to a rupture of an aneurism which, though the consequence of a disease, was precipitated by "some episode or incident in the worker's employment" of the kind to which his Honour referred in Kavanagh. Far from throwing any doubt on Ockenden, he thought that the decision in Hornsby was governed by what had been said in Ockenden [26]. The distinction between Kavanagh and Hornsby is that there was no progressive disease in Kavanagh which might have been the sole cause of the vomiting and the resultant rupture of the oesophagus.

All of these cases were decided on a term "injury by accident" which has no counterpart in the definition in s 4 of the 1987 Act. Windeyer J described provisions similar to those in s 4 as "quite unlike" the provisions considered in Hornsby [27]. The present case turns not on the "injury by accident" provisions but on a definition that contains an express provision covering diseases and their aggravation, acceleration, exacerbation or deterioration. This definition had its origin in the definition of "injury" in s 6(1) (the general definition section) of the Workers Compensation Act 1926 (NSW) ("the 1926 Act"). That definition expressly included a disease contracted in the course of employment and to which the employment was a contributing factor. Amendments to this definition were made in 1929 [28] and in 1942 [29]. In 1942 the following definition in s6(1) was inserted:

" 'injury' means personal injury arising out of or in the course of employment and includes a disease which is contracted by the worker in the course of his employment whether at or away from his place of employment and to which the employment was a contributing factor but does not, save in the case of a worker employed in or about a mine to which the Coal Mines Regulation Act, 1912-1941, applies, include a disease caused by silica dust."

The Privy Council construed the 1942 definition [30] as excluding diseases from the category of injuries covered by the opening words of the definition: Slazengers (Australia) Pty Ltd v Ivy Phyllis Eileen Burnett [31]. Delivering the advice of the Judicial Committee, Lord Simonds said [32]:

"[I]n the Act, the word 'injury' (unless the context or subject-matter otherwise indicates or requires) must bear a very artificial meaning in that it is to include a disease which satisfies certain conditions and must, therefore, according to ordinary rules of construction, exclude any other disease."

InDarling Island Stevedoring and Lighterage Co Ltd v Hussey [33], Dixon CJ regarded Lord Simonds' statement as containing the ratio of the decision. His Honour said [34]:

"That decision is that the ordinary rules of construction prevail and that the definition excludes from the meaning of 'injury' any other disease than one which satisfies the conditions it expresses."

Fullagar J noted that, although the 1942 amendment changed the requirement that a disease arise out of and in the course of employment to a requirement that the disease be contracted in the course of employment and the employment be a "contributing factor", the change probably did not produce a great deal of difference in practical effect [35]. He then cited the judgment of Jordan CJ in Kellaway's Case [36] on which he commented as follows [37]:

" With regard to Kellaway's Case, it is important to note that Jordan CJ expressed the opinion that all cases of disease must, both under the Act of 1929 and under the Act of 1942, be subsumed under the second part of the definition of 'injury', ie that part of the definition which deals specifically with diseases. A case of disease could no longer be regarded as a case of injury in the general sense of the first part of the definition. His Honour said: 'The portion of the definition of injury beginning with the words "and includes a disease" was inserted to indicate that injury is no longer, in the Act, to be read, by a somewhat forced construction, in a non-colloquial sense wide enough to include disease generally, but is to include it only when it is "contracted" in the conditions specified. ... It follows that if a worker originally contracts a not immediately disabling disease from causes to which his employment does not contribute, and, for causes to which also the employment does not contribute, the disease, by its natural progress, grows worse until it reaches a point at which it disables him or causes his death, his employer incurs no liability to compensation' [38]. So far I would agree with his Honour: indeed, I think it clear that the view which he has expressed is correct."

Fullagar J thus excludes all diseases and their consequences from the definition of "injury" provided the employment has not been a contributing factor. He then discounts the observations of Jordan CJ with reference to acceleration and exacerbation of a disease whilst in the course of employment [39]:

"His Honour, however, went on to say: 'If, however, whilst he is in the course of his employment, the progress of the disease is accelerated or its severity accentuated, by the conditions of the employment, and disability results, he is entitled to receive compensation. ... In the latter type of case, the disabling stage of the disease is contracted in the course of employment and its occurrence is contributed to by the employment'[40]. (The italics are mine). This second proposition of the learned Chief Justice is on its face open to grave doubt. His Honour's first proposition gives full effect to the reference to 'disease' in the definition of 'injury'. His second departs from the language of the definition."

In the same case, Windeyer J said [41]:

"Compensation can be had for incapacity or death which results from disease, only when the disease is one contracted in the course of employment and to which the employment was a contributing factor. Slazengers' Case makes it clear that incapacity or death caused by other diseases is not compensable."

Hussey's Casewas one of a fatal coronary occlusion suffered while on a work-related journey. The occlusion was the consequence solely of a progressive heart disease. The claim for compensation failed.

The next case of importance is Favelle Mort Ltd v Murray [42]. The worker had been sent to work in New York and, while on duty there, was attacked by a virus and contracted meningo-encephalitis. The case was decided on a definition of "injury" that was introduced in 1960 [43] to amend s6(1) of the 1926 Act. That definition extended the definition of "injury" to include "the aggravation, acceleration, exacerbation or deterioration of any disease". It read:

" 'Injury' means personal injury arising out of or in the course of employment, and includes -

(a) a disease which is contracted by the worker in the course of his employment whether at or away from his place of employment and to which the employment was a contributing factor; and

(b) the aggravation, acceleration, exacerbation or deterioration of any disease, where the employment was a contributing factor to such aggravation, acceleration, exacerbation, or deterioration;

but does not, save in the case of a worker employed in or about a mine to which the Coal Mines Regulation Act, 1912, as amended by subsequent Acts, applies, include a disease caused by silica dust, or the aggravation, acceleration, exacerbation or deterioration of a disease caused by silica dust".

Speaking of decisions in other jurisdictions in which it had been held that the contraction of a disease resulting from an invasion of the body by bacillus is an injury [44], Mason J said [45]:

"However, it has been affirmatively established that this construction cannot be placed upon the definition of 'injury' in s6 of the Act because the extended definition which it contains includes certain diseases only."

His Honour referred to Lord Simonds' dictum in Slazengers' Case and added [46]:

" Subsequently, in Darling Island Stevedoring and Lighterage Co Ltd v Hussey, as I read the judgments, no less than four members of this Court, after referring to Lord Simonds' observations, expressed the opinion that compensation is not recoverable 'unless the disease possesses the characteristics prescribed' by the statutory definition, per Fullagar J [47]; see also [48]. In view of this strong body of opinion I do not think that we are justified in now adopting a contrary view."

Stephen J, who agreed with Mason J, added [49]the observation that -

"For it to be an 'injury' it must be shown to satisfy the requirements of par (a) of the definition of 'injury' in s 6 of the Act."

Barwick CJ agreed that that view was compelled by authority, although he would otherwise have favoured an interpretation that "an external excitement initiating a morbid condition of the body" would be an "injury" apart from the extension of the definition by par (a) [50]. In identifying the diseases which, in his Honour's view, were referred to by par (a), he said [51]:

"Autogenous or idiopathic changes in the body, if the employment contributed to their onset - and now by par (b) of the definition, to their progression - are thus brought within the meaning of injury. I might add here that par (b) is not limited to autogenous or idiopathic diseases. It expressly extends to any disease so that the aggravation etc of an externally caused disease may constitute an injury."

Jacobs J [52]accepted that the actual entry of the virus was an "injury" either within the opening words of the definition or within par (a) of the 1926 definition (par (i) of the 1987 definition) and McTiernan J [53] held that, in contracting meningo-encephalitis, the worker received an injury but did not find it necessary to discuss whether pars (a) and (b) of s6(1) removed all diseases from the definition of injury unless they possessed the characteristics prescribed by that definition. It was immaterial to the result in Favelle Mort whether the contracting of the disease, as distinct from its progress or consequences, was covered only by par (a) of the definition or fell within the general conception of "personal injury" in the opening part of the definition. The contraction of the worker's disease was "in the course of his employment" and, as he was required to be at the place where the disease was contracted, his "employment was a contributing factor". What is important, however, is the view that the consequences of a disease mentioned in par (b) of the definition are covered, if at all, exclusively by that paragraph.

Favelle Mortwas followed by this Court when it applied the definition of "injury" in s3(1) of the Workers' Compensation Act 1916-1982 (Q) in Hockey v Yelland [54]. The definition in the Queensland Act was relevantly in the same form as the definition considered in Favelle Mort. The worker in Hockey v Yelland [55]had been attended by a doctor who certified that the worker " 'is suffering from cerebral haemorrhage - ie subarachnoid haemorrhage which he states is caused by carrying bricks and a bucket of cement 6 April 1982 at 11.30am' " and " 'is suffering from ruptured cerebral aneurysm which he states is caused by lifting and carrying at work 6 April 1982' ". His case was referred to the

Neurology Board which decided that "the matters alleged by the [worker] do not constitute an injury within the meaning of the Act" [56]. When that decision was challenged on certiorari, the challenge failed. Gibbs CJ, following the line of cases earlier discussed, said [57]:

"I see no reason to doubt the correctness of the construction placed upon the definition in those cases, but even if, contrary to my present view, a disease which is not autogenous, but is caused or exacerbated by an external stimulus, can come within the description of injury simpliciter and so within the opening words of the definition, it is clear that an autogenous disease which happens to manifest itself in the course of employment is only an 'injury' if it comes within par (a) or par (b)."

His Honour contrasted the natural progression of an autogenous disease with an injury which is externally caused to a worker who suffers a weakness occasioned by a disease. He said [58]:

"On the one hand, if an autogenous disease naturally progresses until it results in incapacity, there is no injury within the opening words of the definition: if the incapacity is to be compensable it must fall within par (a) or par (b). On the other hand, a sudden identifiable physiological change may be an injury if it results from some external cause during the course of the employment." (Emphasis added.)

This echoes the observation of Fullagar J in Hornsby in the context of a different definition. Mason J [59] and Brennan J [60]agreed with Gibbs CJ. Wilson J was of the same view, saying [61]:

"There may remain a question as to whether Slazengers' Case should be confined to cases of autogenous diseases or applied to all diseases, however induced; different opinions on that question were expressed in Favelle Mort Ltd v Murray. But here we are concerned with an autogenous disease and therefore it follows, on the authority of Slazengers' Case and Hussey, that for the appellant to succeed he had to persuade the Board that he had suffered a disease which satisfied either par (a) or par (b) of the definition of 'injury'. The question has only to be stated in that way for it to spell the fate of this appeal."

Dawson J [62]agreed with Gibbs CJ and Wilson J. Certiorari did not go to the Board because, as Gibbs CJ said, it was open to the Board to decide, irrespective of the terms of the medical certificates, that the ruptured aneurism -

"was merely 'the culmination or climax of a progressive disease, itself unrelated to employment', to use the words of Windeyer J in Darling Island Stevedoring and Lighterage Co Ltd v Hussey [63], or that the haemorrhage was otherwise autogenous, and that the work which the appellant was doing played no part in causing it, it was quite right to determine that it was not an 'injury' within the meaning of the Act. If they took that view, the haemorrhage was not an injury within the opening words of the definition, and was not within par (a) or par (b) because the employment was not a contributing factor. There is nothing on the record to show that they did not take such a view." [64]

In our opinion, the reasons for judgment in Hockey v Yelland compel the dismissal of the present appeal. The essential steps in the reasoning are not only established by a consistent and unbroken line of authority; they are dictated by the definition of "injury" in the 1987 Act. That definition is not relevantly different from the definition of "injury" in the 1926 Act as it stood after the 1960 amendment [65] although it differs from those Acts in which liability depends on the occurrence of an "injury by accident".

By judicial decision, the consequence of a progressive disease had been excluded from the cover of "injury by accident" if there were no cause of the consequence other than the progress of the disease. It did not matter that the consequence was gradual or was a sudden and distinct physiological change. If there were no underlying disease, however, a sudden and distinct physiological change could amount to "injury by accident" even though there were no external cause for the change. When liability was made to depend on a definition in the terms to be found in the 1926 Act - at least from the time of the insertion of the 1929 amendment - diseases and their consequences were removed from

the category of "personal injury" in the opening words of the definition of "injury" and were covered exclusively by the forerunner or equivalent of the provisions now found in sub-pars (i) and (ii) of s 4(b) of the 1987 Act. The steps in the reasoning which lead to this conclusion appear in Hockey v Yelland. They are these:

1. Diseases and their consequences are added to the categories of "injury" covered by par (a) where the particular disease is contracted "in the course of employment and to which the employment was a contributing factor" or "where the employment was a contributing factor" to the consequence.

2. Diseases and their consequences are not otherwise included in the definition.

3. Hence a consequence solely of a progressive autogenous disease is not an "injury".

There seems to be no substantial difference between the statutory definition of "injury" in s4 of the 1987 Act and the judicial interpretation of "injury by accident" arising in the course of employment.

The change in the drafting of the definition of "injury" in the 1987 Act and its separation from the general definition section are said by the appellant to warrant a departure from the interpretation of "injury" attributed in the cases above cited. Nothing in the revised drafting warrants such a departure. It can be accepted that, by introducing par (b) with the word "includes", the categories of "injury" are extended beyond and do not contract the categories of "personal injury" in par (a) [66]. But, as a matter of construction, diseases and their consequences are covered exclusively by sub-pars (i) and (ii) and their inclusion within the meaning of the term "injury" is conditioned on their possessing the characteristics therein expressed. Indeed, the insertion of "and" after par (b) of the definition and the division of the definition into paragraphs and sub-paragraphs makes it clear that the components of the definition of "injury" are to be ascertained by reference to the distinct and mutually exclusive categories contained in pars (a), (b) and (c).

If the worker were to succeed in the present appeal, it could be only on the footing that a rupture of his aneurism did not fall within any of the categories of "aggravation, acceleration, exacerbation or deterioration" as those categories appear in sub-par (ii) of par (b). That construction is difficult to accept. It would mean that a gradual deterioration in a disease to which employment was not a contributing factor would not be compensable but a sudden deterioration without that contributing factor would be compensable. So adventitious an operation of the 1987 Act should be rejected. As the rupture of the appellant's aneurism falls within the concepts of "aggravation, acceleration, exacerbation or deterioration" as those categories appear in par (b)(ii) of the definition, the Court of Appeal was right to remit the matter for determination of the question whether his employment was a contributing factor to the rupture.

We would dismiss the appeal.

TOOHEY, McHUGH AND GUMMOW JJ.

The principal issue raised by this appeal from the New South Wales Court of Appeal concerns the meaning of "injury" in s4 of the Workers Compensation Act 1987 (NSW) ("the Act"). If the Court were disposed to answer this question favourably to the appellant, further questions arise. The first is whether the decision of this Court in Hockey v Yelland

[67] (on appeal from the Full Court of the Supreme Court of Queensland) would have to be overruled in order to give effect to the appellant's argument. If so, the next question is whether the decision should be overruled, it being a unanimous decision of the Court which has been acted on by those affected by payments of workers compensation including insurers.

The appellant had been working for the respondent since January 1987. On 15 October 1987, shortly after his lunchbreak, he collapsed at work. He was taken to hospital where he was diagnosed as having suffered a cerebral aneurism and thereafter a stroke. Dr Moloney, the neurosurgeon who operated on the appellant, described what had happened as

"a rupture of an anterior communicating artery aneurysm which caused an intracerebral clot and occlusion of the right anterior cerebral artery".

Dr Moloney operated to evacuate the clot and to place a clip about the neck of the aneurism. The appellant has made a slow but progressive recovery. However it is unlikely that he will work again.

The appellant's claim for compensation under the Act was allowed by the Compensation Court. The Court of Appeal set aside the award made in favour of the appellant and remitted the matter to the Compensation Court for rehearing. The reason why the Court of Appeal took that course will appear shortly.

Section 4 of the Act reads:

" In this Act -

'injury' -

(a) means personal injury arising out of or in the course of employment;

(b) includes -

(i) a disease which is contracted by a worker in the course of employment and to which the employment was a contributing factor; and

(ii) the aggravation, acceleration, exacerbation or deterioration of any disease, where the employment was a contributing factor to the aggravation, acceleration, exacerbation or deterioration; and

(c) does not include (except in the case of a worker employed in or about a mine to which the Coal Mines Regulation Act 1982 applies) a dust disease, as defined by the Workers' Compensation (Dust Diseases) Act 1942, or the aggravation, acceleration, exacerbation or deterioration of a dust disease, as so defined."

The appellant contended that he had suffered "personal injury" in the course of employment and that therefore he had received an "injury" within par (a) of the definition. The Compensation Court accepted that contention; the Court of Appeal rejected it. The Court of Appeal took the view that pars (a) and (b) are mutually exclusive and held, in effect, that because the appellant suffered a "disease injury" his claim could only succeed if employment was a contributing factor as required by par (b). Because the question of employment as a contributing factor had not been considered by the Compensation Court the matter was remitted to that Court for rehearing.

At the forefront of the appeal is a question of construction of s 4. The appellant says that if there is personal injury as described in par (a) the inquiry need proceed no further. If there is not personal injury as described he must rely on par (b) in which case the question of employment as a contributing factor has to be considered. But, he says, the two paragraphs are not mutually exclusive, nor is par (b) to be read as limiting what otherwise would be within the reach of par (a); they simply provide two bases upon which a claim may succeed. The respondent answers that this approach involves an unwarranted fragmentation of the definition of injury. The definition must be read as a whole and if the worker has contracted a disease (and an aneurism is a disease) the worker must establish employment as a contributing factor.

The Court was taken to earlier statutes of New South Wales to show how the question of injury or personal injury had been dealt with and to decisions construing the relevant provisions of those statutes and like provisions in the laws of the Commonwealth and other States. Some reference to those provisions and decisions is necessary, mainly because of the respondent's argument that Hockey v Yelland is an obstacle to the success of this appeal. But the first inquiry must be as to the language of s 4 and the proper construction to be placed on that language. However it is of some importance to note that the definition of "injury" now finds its place in its own section and not, as in the past, in the definition section [68]. The repositioning of the definition lends support to the argument that here is a new section, to be construed according to its terms. Not surprisingly perhaps, the respondent argued that the legislature must be taken to have had Hockey v Yelland in mind when enacting s 4. But that is an argument which carries

little force in contemporary society where parliamentary processes are more exposed to examination by the courts. In R v Reynhoudt [69] Dixon CJ said:

"[T]he view that in modern legislation the repetition of a provision which has been dealt with by the courts means that a judicial interpretation has been legislatively approved is, I think, quite artificial".

This passage was referred to by Mason ACJ, Wilson and Dawson JJ in Flaherty v Girgis [70]. Their Honours said:

"Whilst it is true that, where an inference can be drawn from the terms in which subsequent legislation has been passed that Parliament itself has approved of a particular judicial interpretation of words in an earlier statute, a court should adhere to that interpretation, the difficulty is in discerning the existence of parliamentary approval: see Geelong Harbour Trust Commissioners v Gibbs Bright & Co [71]. Mere amendment of a statute not involving any re-enactment of the words in question could seldom if ever constitute approval of an interpretation of those words. Even re-enactment of the words in circumstances not involving any reconsideration of their meaning, as eg, in a consolidating statute, does not do so: Williams v Dunn's Assignee [72];Melbourne Corporation v Barry [73]. At most the principle affords a presumption of no great weight concerning the meaning of the words used and cannot be relied upon to perpetuate an erroneous construction ...

For the reason given by Dixon CJ, the suggested rule nowadays is little use as a guide and it will not be permitted to prevail over an interpretation otherwise appearing to be correct."

The layout of the definition in s4, which differs from its predecessor, certainly suggests that the first inquiry is whether there has been personal injury, a term which itself is not defined and which therefore must be understood according to ordinary concepts. For present purposes, par (c) can be put to one side. That exclusion is explained by the existence of other legislation dealing expressly with dust disease. That par (a) begins with the word "means" and par (b) begins with the word "includes", suggests that par (b) is designed to give an extended meaning to "injury" by going beyond personal injury and to a disease in the circumstances prescribed [74]. In particular, there is no rule of construction which requires inclusive words to be read as exclusive of any elements which otherwise fall within the meaning of the word or expression being defined [75], and no occasion with this legislation for the imposition of such a construction.

It is clear, at least since Kavanagh v The Commonwealth [76], that there may be injury by accident although the injury is not attributable to any external agency but results from some force or pressure exerted from within the body. The Act with which we are concerned does not require that there be an accident, only that there be injury. In Kavanagh a Commonwealth employee suffered a ruptured oesophagus and died six days later as a result of broncho-pneumonia and heart failure supervening upon the rupture. The Court held that personal injury by accident had been caused to the employee in the course of his employment. In determining the question of whether the rupture of the gullet was in the circumstances an injury by accident, Dixon CJ said [77]:

"In my opinion it must be so considered. It is a sudden destruction of tissue by force or pressure. It is true that the force or pressure was not exerted from without the body, but that I think makes no difference nor does it make any difference if it occurred, as it may have done, as a consequence of another organ of the body, namely the stomach, responding to a virus infection".

Fullagar J said [78]: "It is not, I think, open to serious question that the rupture of the oesophagus ... was a 'personal injury by accident'." His Honour went on [79] to construe the phrase "personal injury by accident" which differs from the definition with which this case is concerned, by referring to "a special class of case", such as a coronary occlusion, which is a development or culmination of an antecedent morbid condition. He said that the physiological change constituted by the occlusion must be associated with some incident or episode in the worker's employment, such as lifting a heavy weight, before it can be said the worker has suffered a personal injury by accident arising in the course of

his employment. Menzies J said [80]: "There is no doubt that the rupture was personal injury by accident". We do not understand the dissenting judges, Taylor and Windeyer JJ, to have thought otherwise. Thus, Windeyer J said [81]:

"The rupture which was the unlikely and untoward result of vomiting caused by some sudden indisposition was, I have no doubt, an 'injury by accident' in the sense that expression has in this branch of the law. It was quite unlike an episode that is an ordinary consequence of the progress of a disease".

Their Honours' dissent was because they did not think there had been personal injury by accident in the course of the deceased's employment.

Judgment in The Commonwealth v Hornsby [82]was delivered the same day as Kavanagh. The Court there held that the stroke which incapacitated the respondent was a result solely of the natural progression of a pre-existing morbid condition and did not constitute injury by accident. However, in his examination of the authorities, Fullagar J referred [83], as an example of personal injury by accident, to "the rupture of an aneurism or of an oesophagus". He added: "It has been said, naturally enough, that the breaking of an artery cannot be distinguished from the breaking of a leg."

In the present case Dr Stening, a neurosurgeon, examined the appellant. He described an aneurism as "an area of weakness of a blood vessel wall ... supplying the brain". He thought it almost certain that the weakness in the appellant's case was congenital. He described the rupture in the following terms:

"The weakness of the blood vessel wall balloons out [so] that it assumes the shape of a berry, and as it balloons out the rounded part of the swelling becomes thinner and thinner until finally the pressure of the blood behind it tears it. What usually happens is that an amount of blood leaks from the blood vessel into the fluid surrounding the brain which causes immediate intense headache and often immediate loss of consciousness. In the fortunate people the blood's clotting mechanisms stop that bleed from progressing, and there is if you like, a stay of execution, but eventually that blood clotting mechanism breaks down and then there is a major rupture which is usually fatal."

InHume Steel Ltd v Peart [84], Latham CJ said:

"There is a distinction, according to the common use of language, between getting hurt and becoming sick. The former would be described as an injury and the latter would generally not be so described. But it requires little analysis to show that an injury may be either external or internal. It appears to me to be difficult to draw any satisfactory distinction between the breaking of a limb and the breaking of an artery or of the lining of an artery. One is as much an injury to the body, that is, something which involves a harmful effect on the body, as the other. Each is a disturbance of the normal physiological state which may produce physical incapacity and suffering or death. Accordingly, in my opinion the detachment of a piece of the lining of the artery in the present case should be held to be an injury."

The personal injury upon which the appellant relies is the rupture of the arterial wall. There can be no doubt, having regard to the medical evidence and the authorities to which we have referred, that this event constituted personal injury and it is not in dispute that what occurred took place in the course of the appellant's employment. Equally it is not in issue that the aneurism itself, that is the swelling of the blood vessel, was a disease from which the appellant was suffering prior to the rupture. Does the existence of this disease take the matter into par (b) of the definition so that the appellant must show his employment to have been a contributing factor?

The respondent relies upon Hockey v Yelland in answer to the proposition that personal injury may be considered independently of the question of disease. The statute there under consideration was the Workers' Compensation Act 1916 (Q). Gibbs CJ described the relevant provision in these terms [85]:

" The definition of 'injury' in s3(1) of the Act comprises three categories - (1) personal injury arising out of or in the course of employment within the opening words of the

definition, where the word 'injury' is used in its ordinary or unextended sense; (2) a disease within par (a) of the definition; (3) the aggravation or acceleration of a disease within par (b)."

It is important to appreciate in that case the way in which the appellant's claim came before the courts. The appellant suffered a subarachnoid haemorrhage while working as a labourer on a building site. His claim for compensation was referred to the Neurology Board pursuant to a provision of the Queensland statute. The Board determined that "the matters alleged by the claimant do not constitute an injury within the meaning of the Act". The Board did not and was not obliged to, give any reasons for its determination which by the statute was declared to be "final and conclusive". The appellant, alleging error on the face of the record, sought by certiorari to have the determination quashed. The Court held unanimously (Gibbs CJ, Mason, Wilson, Brennan and Dawson JJ) that there was no error of law on the face of the record and that certiorari was rightly refused by the Supreme Court. Mason, Brennan and Dawson JJ agreed with the judgment of Gibbs CJ.

The appellant's case was that the subarachnoid haemorrhage was an injury in the unextended sense of the definition. As to this Gibbs CJ said [86]:

"The importance of this question lies in the fact that the Neurology Board may have taken the view that the subarachnoid haemorrhage was autogenous and that stress or exertion was not a contributing factor in causing it. So to decide would not be an error of law on the face of the record."

Having examined a number of authorities, his Honour concluded [87]:

"It follows from what I have said that if the Neurology Board decided that the subarachnoid haemorrhage was merely 'the culmination or climax of a progressive disease, itself unrelated to employment' ... or that the haemorrhage was otherwise autogenous, and that the work which the appellant was doing played no part in causing it, it was quite right to determine that it was not an 'injury' within the meaning of the Act. If they took that view, the haemorrhage was not an injury within the opening words of the definition, and was not within par (a) or par (b) because the employment was not a contributing factor. There is nothing on the record to show that they did not take such a view."

There can be no quarrel within this passage from the judgment of Gibbs CJ so long as the confined context in which it is expressed is clearly understood. If nothing more appeared than that the haemorrhage was merely the culmination or climax of a progressive disease, it could not be said that the rejection of the claim by reference to the opening words of the definition disclosed an error on the face of the record. But that is not the present case. Wilson J delivered a separate judgment but again that judgment was circumscribed by what his Honour described [88] as "[t]he difficulty confronting the appellant [of finding] an error of law on the part of the Board and to do so without taking the Court beyond the record into all the circumstances of the case." His Honour also referred to a number of authorities including the decision of the Privy Council in Slazengers (Australia) Pty Ltd v Burnett [89]and said [90]:

"There may remain a question as to whether Slazengers' Case should be confined to cases of autogenous diseases or applied to all diseases, however induced; different opinions on that question were expressed in Favelle Mort Ltd v Murray [91]. But here we are concerned with an autogenous disease and therefore it follows, on the authority of Slazengers' Case and Hussey [92], that for the appellant to succeed he had to persuade the Board that he had suffered a disease which satisfied either par (a) or par (b) of the definition of 'injury'. The question has only to be stated in that way for it to spell the fate of this appeal."

InDarling Island Stevedoring and Lighterage Co Ltd v Hussey the Court held that the effect of the decision in Slazengers' Case was that the definition of injury in the 1926 New South Wales statute did not cover a case of disease unless employment was a contributing factor.

But the present case is not one of an autogenous disease. Or, to put it more accurately, it is not an autogenous disease upon which the appellant relies. It may be accepted that

the aneurism was an autogenous disease but the appellant's claim to personal injury within par (a) is based on the rupture which occurred. From Dr Stening's evidence, it is clear that the rupture of the aneurism was not inevitable and further that the rupture may have been minor, allowing the appellant, after treatment, to return to his previous occupation. If there was no rupture there would be no event answering the description of personal injury and the appellant would be driven to rely upon par (b) of the definition. But there was such an event and the presence of a disease does not preclude reliance upon that event as personal injury.

The word "disease" has been considered by this Court in a number of decisions, including Favelle Mort Ltd v Murray where Barwick CJ said [93]:

"The word 'disease' is itself a word of some difficulty in this context, particularly in the expression 'contraction of a disease'. Properly used, disease denotes a morbid condition of the body. It may be initiated by some external cause or be idiopathic or autogenous."

But the word must be seen in the context in which it appears and be related to the circumstances of the case. To say that the aneurism was a disease does not answer the question whether the rupture itself can fairly be described as an injury.

Thus in Darling Island Stevedoring and Lighterage Co Ltd v Hankinson [94] a worker suffered pain and later paralysis caused by the collapse of one or two infected vertebral bodies. The consensus of medical opinion was that the infection, unless discovered and treated successfully, would in the ordinary course of events have progressed ultimately to produce a collapse of the vertebrae and incapacity. The Workers' Compensation Commission treated the matter as an aggravation, acceleration, exacerbation and deterioration of a pre-existing disease. However this Court held that the collapse of the vertebrae was an "injury" in the ordinary sense without resort to the extended definition in s 6(1)(b) of the Workers' Compensation Act 1926 (NSW). The decision is mentioned in Hockey v Yelland [95]without any doubt being cast on its correctness.

InO'Neill v Lumbey [96] the respondent suffered a rupture of two aneurisms which occurred in his right cerebral artery, causing haemorrhaging into the intracranial space. The Court of Appeal (Priestley and Clarke JJA, Kirby P dissenting) held that the respondent had received an injury in accordance with the definition of injury in s6(1) of the Workers' Compensation Act 1926 (NSW), that is, personal injury within the unextended meaning of that term. It is clear enough that Kirby P would have reached the same conclusion had he not felt constrained by authority, particularly Slazengers' Case.

InAccident Compensation Commission v McIntosh [97] the Appeal Division of the Supreme Court of Victoria held that it was open to the Accident Compensation Tribunal to find that the sudden rupture of blood vessels and consequent cerebral haemorrhage, arising from an arteriovenous malformation, was a "physical injury" under the relevant Victorian statute. Murphy J, with whom Crockett and Cummins JJ agreed, pointed out that there was general agreement that if some external agency precipitates a rupture, it is a physical injury. But, as his Honour observed [98]:

"If the rupture is due to blood pressure, arteriosclerosis, arteriovenous malformation, or any other congenital or diagnostic aetiology, it is nonetheless a rupture - something quite distinct from the defect, disorder or morbid condition, which enables it to occur."

We respectfully agree with this observation and, in our view, nothing in Hockey v Yelland or in any other decision of this Court precludes its acceptance.

We would allow the appeal, set aside the decision of the Court of Appeal and dismiss the appeal to that Court.

KIRBY J.

Mr Darrin Zickar (the worker) on 15 October 1987, whilst at work, sustained a subarachnoid haemorrhage, together with an intracerebral clot consequential on a bleed from an aneurism in the right anterior communicating artery. He claimed, and was awarded, compensation by the Compensation Court of New South Wales (Judge

Thompson). The award was recovered on the basis that the worker had sustained an "injury" within the first paragraph of the definition of that word in s4 of the Workers Compensation Act 1987 (NSW) (the 1987 Act).

MGH Plastic Industries Pty Limited (the employer) appealed to the Court of Appeal of the Supreme Court of New South Wales. That Court (Meagher and Powell JJA; Priestley JA dissenting) allowed the appeal. It set aside the award and remitted the proceedings to the Compensation Court for the reconsideration of the claim within the second part of the definition of "injury" in the 1987 Act, which deals with the consequences of diseases.

The worker, by special leave, has appealed to this Court. The hearing of the appeal commenced before the Court differently constituted. When it became plain that the worker's argument might raise the suggestion that the Court should overrule statements of the law by the Privy Council in Slazengers (Australia) Pty Ltd v Burnett

[99]and by this Court in Hockey v Yelland [100], further argument of the appeal was reserved to the Court as presently constituted.

The appeal raises a point of importance concerning the approach of Australian courts to the definition of "injury" in workers' compensation law. Although such definitions, in the applicable federal and State enactments, are not identical, typically the word "injury" now receives both a primary definition and an extended definition dealing with diseases.

As presented by the worker, the case was simple. He had suffered an "injury" in the primary sense. What had occurred was a "sudden or identifiable physiological change which could properly be described as a personal injury, not being a disease" [101]. It was therefore unnecessary to go to the extended definition of "injury". The employer contended that such an approach was forbidden by the authority of the Privy Council in Slazengersand of this Court in Hockey.

The issues

Three issues thus arise in the appeal:

1. Does past authority require that a claim for compensation, such as that made by the worker, be compensable only if it falls within that part of the definition of "injury" in the 1987 Act dealing with diseases?

2. If so, is that past authority correct in law and applicable to the slightly different definition of "injury" in the 1987 Act, by which that definition was assigned to a separate section [102]?

3. If not, should the Court refrain from giving effect to such an opinion out of deference to the contrary opinion of the Court in Hockey; the need for certainty and stability in the law [103]; and the restraint proper to a court in altering the understanding of the meaning of legislation of widespread application which has substantial economic significance for the fixing of premiums and the assessment of risks?

I have little difficulty in answering the first two questions. It is the third which presents the problem.

The judgments under appeal

In the Compensation Court, Judge Thompson recounted the relevant facts. The worker had previously enjoyed good health. His only symptoms had been headaches, for which he took aspirin. The intracerebral incident which occurred to him at work caused him to collapse. He was taken by ambulance to Wollongong Hospital where an aneurism was diagnosed, operated upon and "clipped". At operation, Dr Peter Moloney found the haemorrhage and clot. He concluded that these were the result of a rupture of the aneurism. The medical evidence, accepted by Judge Thompson, showed that congenital aneurisms, of the kind found in this instance, involve "an inborn error". Eventually the aneurism becomes sufficiently weak that it actually tears under normal blood pressure. Rising blood pressure can contribute to a tear with the catastrophic consequences which usually follow.

There are different types of aneurisms, including the degenerative "atherosclerotic" variety. However, these were excluded in the worker's case. The judge recorded:

" It was not suggested by either party that the aneurysm is, or was, a disease ...

I accept the opinions expressed by the applicant's doctors, and even those of the respondent's doctors that the development of the aneurysm and the rupture was not a disease.

I am satisfied the applicant had a congenital weakness which, with the passage of time, led to the production of the aneurysm which in time inevitably ruptured. It was submitted that the applicant suffered an injury simpliciter and I am satisfied that he did suffer an injury simpliciter and not a disease."

In coming to his conclusion, Judge Thompson relied on the decision of the New South Wales Court of Appeal in O'Neill v Lumbey [104]. He awarded the worker compensation on the basis of total incapacity.

In the Court of Appeal, Meagher JA rejected the invitation to follow O'Neill. His basic reason was that he regarded it as "having been wrongly decided and as inconsistent with High Court authority". In support of this opinion, his Honour referred to Darling Island Stevedoring and Lighterage Co Ltd v Hussey [105]which he took to have affirmed the test for the categorisation of injuries simpliciter and disease injuries formulated by Lord Simonds in Slazengers [106]. Powell JA acknowledged that the area of the law under consideration was "replete with artificialities and distinctions which are so exquisitely fine that they would provide many hours of diversion for a seminarian". He concluded that the worker's underlying condition was "a disease" as that word had been widely construed in the authorities. Being such, the case had to be considered under the separate part of the definition of "injury" applicable to "diseases". There being no consideration by Judge Thompson of whether the worker could succeed on the footing of an employment-caused aggravation of his "disease injury", it was ordered that the proceedings be remitted to the Compensation Court.

Priestley JA, in dissent, followed the line of reasoning of Clarke JA, with whom he had agreed in O'Neill. He drew on the opinion of Fullagar J in The Commonwealth v Hornsby [107]. He concluded that nothing said in Hussey about coronary occlusions required that a rupture of a cerebral artery must be classified as a "disease injury", entitling the worker to compensation only if it came within the statutory qualifications for that class of "injury". Not only was it open to the primary judge to conclude as he did. It was the correct view of the facts in the evidence accepted by him.

The statutory definition of injury

To resolve the first of the issues which I have identified, it is useful to start with the successive definitions of "injury" under New South Wales workers' compensation legislation.

TheWorkmen's Compensation Act, 1916 (NSW) provided in s 5(1):

"If in any employment personal injury by accident arising out of and in the course of the employment is caused to a workman, his employer shall, subject as hereinafter mentioned, be liable to pay compensation ..."

Section 12 of that Act provided for recovery of compensation in certain circumstances of scheduled industrial diseases where:

"the disease is due to the nature of any employment in which the workman was employed at any time within the twelve months previous to the date of the disablement ..."

In such a case the "disablement" was to be treated as the happening of the "accident" [108].

TheWorkers' Compensation Act 1926 (NSW) (the 1926 Act) introduced important changes. It dropped the requirement of proof of an "accident". This swept away one of the major impediments to recovering compensation in disease cases [109]. However, as

originally enacted, the definition of "injury" required proof of a temporal and causal connection with the employment:

"... personal injury arising out of and in the course of the employment and includes a disease so arising whether of sudden onset or of such a nature as to be contracted by gradual process other than a disease caused by silica dust." [110]

In 1942 this definition was, in turn, replaced by the following:

"... personal injury arising out of or in the course of the employment and includes a disease which is contracted by the worker in the course of his employment whether at or away from his place of employment and to which the employment was a contributing factor ... ." [111]

The introduction of the disjunctive "or", following so closely upon the removal of the need to show an "accident", presented the problem of whether or not compensation could be recovered where a sudden pathological change took place, which was internal and was in some way connected with an ongoing pathological condition personal to the worker.

Past authority on disease injuries

InHume Steel Ltd v Peart [112]this Court had little difficulty in resolving that problem. The worker there had died whilst on a journey to his place of employment from his place of abode as a result of a coronary occlusion to which the effort of the journey had contributed. The Court held that the definition of "injury" in s6(1) of the 1926 Act was not applicable to the word "injury" appearing in the journey provisions of s 7(1)(b). Latham CJ gave full weight to the word "includes". His Honour observed [113]:

"... diseases are excluded from the English Act, not because they are not injuries, but because the onset and development of such a disease cannot be brought within the conception of the word 'accident' ... Thus in England it has been held that if the death of a workman is attributable solely to disease, then it cannot be said to be due to accident. In such a case there is nothing unexpected. But the exclusion of such cases from the category of accidental injury does not show that they are to be excluded from the category of injury.

There is a distinction, according to the common use of language, between getting hurt and becoming sick. The former would be described as an injury and the latter would generally not be so described. But it requires little analysis to show that an injury may be either external or internal. It appears to me to be difficult to draw any satisfactory distinction between the breaking of a limb and the breaking of an artery or of the lining of an artery. One is as much an injury to the body, that is, something which involves a harmful effect on the body, as the other. Each is a disturbance of the normal physiological state which may produce physical incapacity and suffering or death."

Dixon J agreed in this approach [114]:

"I am unable to agree in the argument that was advanced founded upon the express reference in the definition of 'injury' to diseases contracted in the course of the employment to which the employment is a contributing factor. That argument was that the only disease or pathological state or change covered by s7(1), whether under the head of 'injury' or otherwise, is that described in the reference to disease contained in the definition of 'injury'.

It must be remembered that the words in question were introduced to enlarge the scope of the definition. I think a restrictive inference of so drastic a kind cannot be based upon them."

Starke, Rich and McTiernan JJ adopted a like approach [115]. There was thus a unanimous opinion of this Court, essential to the determination of the appeal in Peart, that the extension of the definition of "injury" to include certain diseases did not deprive the worker of the entitlement to bring his claim within the primary definition of "injury", if he could do so.

Into this settled state of Australian legal authority intruded the decision of the Privy Council in Slazengers. In effect, that decision overruled Peart. The worker proved that a

coronary occlusion had occurred on his journey to work. But he did not prove that effort had played a part. It was held that the definition of "injury" in s6 of the 1926 Act did apply to the word when used in s7(1)(b) of that Act. It was further held that the worker had not received an "injury" within the definition. Lord Simonds said [116]:

"[I]n the Act the word 'injury' (unless the context or subject-matter otherwise indicates or requires) must bear a very artificial meaning in that it is to include a disease which satisfies certain conditions and must, therefore, according to ordinary rules of construction, exclude any other disease."

Upon this reasoning, as Gibbs CJ pointed out in Hockey [117], "a disease is only included in the definition if it comes within the words" of the secondary part of the definition, dealing specifically with disease type cases.

At the time it was pronounced, Slazengers, being a decision of the Privy Council, bound this Court. Unsurprisingly, it was followed in Hussey, also a case involving a coronary occlusion suffered by a worker on his journey to work. The Court there held that the coronary occlusion was to be classified as falling within the definition of "disease" because that word included "what would ordinarily be regarded as a pathological condition continuing to operate according to its pathological nature" [118]. The Court rejected the notion that a worker "contracted" a disease in the course of his employment simply because the disease progressed, while at work, to a new and disabling stage [119]. It was this view of the limitation of the notion of "contracting" a disease that led, in due course, to the amendment, designed to overcome Hussey, and to provide compensation benefits for cases of diseases aggravated etc by work related causes.

The conflict between the unanimous approach of this Court in Peart and the controlling decision of the Privy Council in Slazengers, applied in Hussey,was called to attention by Barwick CJ in a powerful opinion in Favelle Mort Ltd v Murray [120]. As counsel, he had successfully argued the Privy Council appeal in Slazengers. But their Lordships did not accept his argument. They struck out on reasoning of their own. Clearly enough, Barwick CJ was unimpressed by it [121]:

" The word 'disease' is itself a word of some difficulty ... Quite clearly, when such a condition is idiopathic or autogenous, it will not qualify as an injury in the normal use of language. The actual decision in Slazengers (Australia) Pty Ltd v Burnett... was an affirmation of precisely that proposition, though the reasons given for it were not those I may venture to suggest. ...

The question then arises as to the effect of the extension of the connotation of the word 'injury' by the inclusive words of par (a) of the definition. If, as I think, the external cause initiating a morbid condition of the body is itself an injury within the ordinary sense of that word, does the extension of the definition in par (a) exclude all disease, both disease externally excited and autogenous disease, from the normal connotation of the word 'injury' itself and merely add to that connotation disease qualifying within the words of that paragraph? The conclusion to which their Lordships came in their reasons in Slazengers ... was that the terms of par (a) of the definition did operate to exclude all diseases which did not satisfy those terms. Their Lordships did not reach this conclusion because of any apparent policy of the legislation dictating such a result: indeed, there was no examination of that policy. Their conclusion was arrived at only by reason of the rules of statutory construction."

And later his Honour said [122]:

"I am unable to perceive any reason, either in rules of construction or in point of policy evidenced in workers' compensation legislation, why the addition of par (a) of the definition should be held to operate to exclude such 'injuries'. It would not, in my opinion, sort well with the known policy of workers' compensation legislation to read words of extension as effecting a restriction of the area of benefit."

Barwick CJ concluded that he should refrain from expressing his view on whether the reasons of the Privy Council should continue to bind this Court to follow and apply them "as of obligation" [123]. Clearly enough, he was of the view that an external excitement, initiating a morbid condition of the body, would be an "injury" in the primary sense,

although an autogenous disease, as such, would not. However, he did not give effect to that view because of his doubts about the continuing operation of the Privy Council holding.

I have excluded from this chronicle several other cases in this Court for they contribute little to the point in issue in the present case. In fairness, I should, perhaps, acknowledge that the Privy Council's approach gained some support from the reasoning of Jordan CJ in Kellaway v Broken Hill South Ltd [124], which had preceded Peart.

The doubts cast by Barwick CJ, and expressed in such strong language, were bound to come before the Court again. This they did in Hockey [125]. That was a case concerned with s3(1) of the Workers' Compensation Act 1916 (Q) (the Queensland Act) which was in terms materially identical to the provisions of the 1926 Act in New South Wales. The essential question before the Court in Hockey did not, as such, concern workers' compensation law at all. It related to the scope of certiorari for error of law on the face of the record of a medical board established by the Queensland Act and whether the board could lawfully conclude that a worker's employment did not contribute to the aggravation or acceleration of the disease from which he suffered. Incidental to the resolution of that question was the issue of whether Favelle Mort had cast sufficient doubt upon the continued application of Slazengers and Hussey, or whether those decisions still stated the law binding on Australian courts. The worker in Hockey had suffered a subarachnoid haemorrhage at work. If, without more, that was sufficient to establish an "injury", an error of law on the face of the record would arguably have been demonstrated.

Whilst noting Barwick CJ's reservations in Favelle Mort Gibbs CJ accepted that the decisions in Slazengers and Hussey applied. There was, in his Honour's view, "no reason to doubt the correctness of the construction placed upon the definition in those cases" [126]. Mason J agreed in the opinion of Gibbs CJ on this point [127]. So did Brennan J [128]. Wilson J also applied Slazengers and Hussey without, in effect, reconsidering their binding force [129]. Dawson J likewise assumed that an autogenous disease which manifested itself during the course of the worker's employment was not an injury under the Queensland Act because "it was not a disease to the aggravation or acceleration of which the employment was a contributing factor" [130]. The Court unanimously dismissed the appeal.

So stood the authority of this Court until the present appeal. Within the appellate courts of the States, some resistance has become evident in recent years to the Slazengers principle. In New South Wales, this resistance was given voice in O'Neill v Lumbey [131]. I dissented from the majority in that decision. I was of a view contrary to that expressed in Slazengers. But I held myself bound by the authority of that decision as accepted and applied by this Court [132]. I expressly acknowledged the artificiality which the binding line of authority required.

Judges in other State courts followed the majority in O'Neill. Thus, in the Full Court of the Supreme Court of South Australia, Legoe, Millhouse and Olsson JJ in Workers Rehabilitation and Compensation Corporation v Ascione [133] held that the rupture of a worker's intracerebral artery, occurring on a journey to work, was not a "disease" or the result of a disease. The word "includes" in the definition of "injury" in the Workers Rehabilitation and Compensation Act 1986 (SA) was held to broaden the ambit of compensable disabilities and not to narrow it. In the Appeal Division of the Supreme Court of Victoria in Accident Compensation Commission v McIntosh [134] it was held that it was open to the Accident Compensation Tribunal of Victoria to find that a sudden rupture of blood vessels, and consequent cerebral haemorrhage, arising from a congenital weakness, was a "physical injury" within the meaning of the Accident Compensation Act 1985 (Vic) (the Victorian Act). Murphy J, in the course of his reasons, effectively repeated what Latham CJ and Dixon J had suggested in Peart and what Barwick CJ had said in Favelle Mort. This was that it would be remarkable if an amendment to the definition of "injury" designed to include certain diseases in given circumstances (and thus to extend the cover of compensation) were to be construed as excluding the primary and ordinary meaning of the word "injury" if it otherwise applied, to an internal, sudden and identifiable pathological change, such as the rupture of a cerebral artery [135]:

" Long before the inclusion of these references to 'disease' in the definition of 'injury', claims for coronary occlusions, cerebral haemorrhage, ruptured aneurysms, aorta, oesophagus etc had commonly been made and had succeeded if occurring during a protected period, on the basis that they were 'injury by accident', being clearly a physical injury - and accidental - being unexpected by the worker at the time that they occurred."

The resulting state of legal authority

For the worker, it was urged that it was open to this Court, consistent with its past authority, to hold that the rupture of his congenital aneurism was an "injury" within the primary definition of that word in the 1987 Act. A number of considerations were said to support such a holding:

1. The re-enactment of the definition of "injury" in a separate section of the 1987 Act (s4). This had emphasised the separate nature of disease injuries by including them in a separate paragraph (s 4(b)). This showed, so it was said, the separate and primary entitlement of the worker to bring his claim within the ordinary definition of "injury" (s4(a)).

2. The state of authority before Hockey was uncertain, and was not finally resolved by Favelle Mort. Some decisions of the Court, such as Darling Island Stevedoring and Lighterage Co Ltd v Hankinson [136] were difficult to reconcile with the acceptance of a complete dichotomy between "injuries" and "disease injuries". This diversity of opinion, and the reservations about Slazengers voiced by Barwick CJ in Favelle Mort, permitted the Court in the present case to return to its earlier line of authority in Peart. By doing so, it could give the primary definition of "injury" its ordinary application, notwithstanding that the present injury was an internal one.

3. So far as Hockey appeared to stand in the way, it was, or was to be classified as, no more than a ruling on the certiorari question there under consideration [137]. It should be so confined and not taken to be a determination of the question now before the Court.

4. After Slazengers, the Court had continued to assume the authority of the reasoning of the Privy Council. In this appeal, it was invited to review that reasoning and to return to its own earlier authority in Peart.

These arguments cannot be accepted:

1. The definition of "injury" in the 1987 Act is, it is true, contained in a separate section. But the substance is exactly the same. All that has changed is that the drafter has broken up a rather long paragraph. The alteration appears to be one of style, not one of substance. No mention of an intended change of substance was made in Parliament.

2. A fair reading of the line of authority to which I have referred indicates that this Court was driven to the view espoused in the reasons of the Privy Council because it considered that this was necessary to give effect to the entirety of the definition of "injury". Only in this way would it reflect the special provisions which had been enacted for "disease injuries". InFavelle Mort, only Barwick CJ expressed reservations concerning the reasoning of the Privy Council. In a string of other cases, that reasoning had been accepted. Gibbs CJ in Hockey expressly stated that he did so not simply because of its authority but because there was no reason to doubt the accuracy of the construction which had been adopted.

3. So far as Hockey is concerned, whilst it is true that it required consideration of the availability of certiorari, the occasion was certainly taken to review the past authority of this Court on "disease injuries". Had a contrary view been taken of the legal approach to be adopted to the statutory definition of "injury" there would arguably have been an error of law on the face of the record as it was defined. At the very least, Hockey evidences a strongly expressed, unanimous and recent opinion of the Court on the approach to be taken to claimed injuries which were properly classified as the end result of a "disease", in the sense of a "pathological condition continuing to operate according to its pathological nature" [138].

4. By the time Hockey was decided, whatever authority the Privy Council decision in Slazengers had previously enjoyed, it had been subsumed by its adoption in Hussey, its application in numerous later cases and its endorsement in Hockey itself.

The present facts do not permit a viable distinction to be drawn from the principles stated in Slazengers, Hussey and Hockey. Hockeyitself was a case of subarachnoid haemorrhage. Unlike Slazengers and Hussey, it was not a case of coronary occlusion. To this point I agree with Brennan CJ, Dawson and Gaudron JJ.

The past authority is erroneous

Notwithstanding this conclusion, I am of the opinion that the authority expressed in Slazengersand Hussey is incorrect. To the extent that it endorsed the approach in those cases, Hockey was also incorrectly decided. The approach originally taken in Peart was correct. Barwick CJ's comments in Favelle Mortare compelling.

The structure of s4 of the 1987 Act makes plain, by the design of the section, what was, in any case, previously clear enough. To add to a definition a special additional ground for securing benefits and to provide that the definition "includes" those grounds does not, on ordinary principles of construction, subtract from the operation of the primary definition according to its terms.

In the Victorian Act [139] this is made clear by the use of the phrase "and without limiting the generality of the foregoing" to provide the link between the primary definition of "injury" and the definition of "disease injury". The Privy Council noticed this distinction in the later case of James Patrick & Co Proprietary Ltd v Sharpe [140]. But their Lordships accepted and approved the decision of the Full Court of the Supreme Court of Victoria in Willis v Moulded Products (Australia) Ltd [141] that a sudden physiological change need not be associated with any external event to constitute a "physical injury" within the primary definition. For a very long time under English legislation, the rupture of an artery had been held to be capable of constituting a "personal injury by accident" [142]. This was because it had the hallmarks of an "injury", being a sudden or identifiable pathological change. The mere fact that it was internal, as distinct from external, did not make it any less an "injury". Many cases of "internal" injuries, having no apparent causative link with work, were held compensable, once the qualifying statutory words rendered it sufficient to prove that the injury arose "in the course of" the employment without the need to show that it arose "out of" the employment. Twisted bowel crises, a ruptured oesophagus following vomiting and other internal injuries attracted compensation [143]. To exclude the sudden rupture of an aneurism because it had no proved causal connection with work is not only inconsistent with this line of authority. It reveals a judicial hankering for the obligations of the conjunctive phrase to qualify for compensation entitlements "arising out of [and] in the course of employment". Those obligations have long since been deleted from the general provisions of the Act. There should be no going back to them.

When the explanation for excluding recovery of compensation in a case such as the present is sought, it is most surprising to see that the addition of an extended definition of "injury" to include certain disease cases is given as the reason. On the face of things, it would appear unlikely that such would have been Parliament's intention, in expanding the scope of recovery for "injuries", to bring about a consequence of excluding from compensable "injuries" a number which had long since been held to fall within the primary definition. Yet that is what, in cases such as the present, Slazengers, Hussey and Hockey have been said to require.

I need say no more on this for, in the matter of substance, my views coincide with those expressed by Barwick CJ in Favelle Mort [144]. If it can properly do so, this Court should therefore return to its own earlier authority in Peartbefore the reasoning of the Privy Council in Slazengers obliged the Court to take a wrong turn.

Approach to overruling past authority

There are important considerations of legal policy, including judicial restraint, which argue against overruling (to the extent necessary) the reasoning in Slazengersand the cases in this Court which have applied its reasoning. Indeed, the employer conceded that, if the Court were "starting afresh", it might take a different approach to the

definition of "injury" in the 1987 Act. The field having been well ploughed, and no large question of constitutional interpretation being involved, the employer submitted that the Court should adhere to its past authority [145]. It should bring the "wayward" State courts into line with that authority.

Amongst the considerations to be weighed by this Court are:

1. The decision in Slazengers was pronounced more than forty years ago. It has been treated as legal doctrine throughout this country and in this Court ever since.

2. As recently as 1984, in Hockey, the decision was specifically referred to and approved, notwithstanding the Court noticing the critical remarks of Barwick CJ in Favelle Mort. That unanimous opinion of the Court should not be lightly disturbed.

3. One construction of the word "includes", as appearing in the definition of "injury", is that it was necessary to refer specifically and additionally to disease cases because they were not already included in the general definition. This construction would suggest that the ordinary meaning of "personal injury" should be read down to exclude disease cases, now specifically provided for but in a limited way.

4. Matters of statutory construction are inherently disputable. It is rare that there is only one approach to resolving an ambiguity. Successor judges, who favour a view different from that earlier expressed, should observe a high measure of restraint, lest an undesirable element of uncertainty be introduced into the law, damaging respect for legal institutions in which future judges, in their turn, override the authority established by them.

5. Restraint is particularly appropriate in an area of the law having national significance which potentially involves multiple applications and hundreds of cases annually depending upon the proper construction of applicable statutes. A decision in the present case would arguably have significance for the assessment of risks of employers throughout the nation. Employers might be exposed to a new risk of liability for the chance manifestations of ruptured aneurisms happening during work hours or on work-related journeys. Such risks would have to be reflected in premium calculations and re-insurance decisions which, it could be assumed, have, until now, been made reliant upon the decisional authority commencing with Slazengers. Any large change in the exposition of such a law might be seen as the province of Parliament rather than of this Court.

6. Parliament has, in fact, had numerous opportunities to amend the law expressed in Slazengers. Indeed, it availed itself of an opportunity to expand workers' entitlements following Hussey by the adoption of what, in the 1987 Act in New South Wales, is now s4(b)(i) of that Act. Had Parliament intended a larger entitlement, in effect to override Slazengers and to provide that every ruptured aneurism and coronary occlusion occurring during work hours, or on a work journey, was to be compensable, it could have so provided in clear terms. By enacting the 1987 Act, effectively with the same definition of "injury", it is conventionally said that Parliament should be taken to have accepted the pronouncements of this Court on the state of the law as made before that time, including in Slazengers, Hussey andHockey [146].

The past authority should be overruled

I have found this the difficult point to resolve in the appeal. I accept that there are very strong reasons in this case for the exercise of restraint [147]. Such restraint would not necessarily defeat the worker's claim. His claim would simply be returned to the Compensation Court to consider whether he could bring his case within the "disease" paragraph of the definition of "injury".

For a number of reasons, I have concluded that the preferable course is to correct the legal error introduced by the reasoning of the Privy Council in Slazengers. Doing so will help to resolve some of the artificial distinctions which have arisen, to which Powell JA drew attention in the Court of Appeal. In particular, it will remove the artificial differentiation between injuries in the nature of the breaking of a leg and the breaking of an artery or the rupture of the bowel and the rupture of an artery wall. My reasons are:

1. Whilst it is true that the authority of Slazengers has stood for forty years, for most of that time it could not, effectively, be questioned because it was binding on this Court and on all other Australian courts. This Court is not now so bound. By chance, in Peart, this Court had earlier expressed its own opinion. That opinion was correct. We should return to it.

2. It is not clear whether the points argued in this appeal were canvassed in Hockey. The short notes of argument [148]suggest that the unsuccessful appellant relied principally on the law of certiorari so that the matters argued in the present appeal may not have been so fully canvassed before the Court. In any case, in 1984, appeals still lay from the Full Courts (and Courts of Appeal) of the State Supreme Courts to the Privy Council. Although, in 1984, this Court was not bound, in a technical sense, by Slazengers the State Courts (including the Full Court of the Supreme Court of Queensland in Hockey) considered that they were. In 1984 this Court would have wished to avoid a dichotomy of legal authority. No such problem arises today. If the Court now considers that the reasoning in Slazengerswas unduly wide, it can say so without embarrassment. This is particularly so because its own earlier authority had been to the contrary of the Privy Council's reasoning. Commentators on workers' compensation legislation, even after Slazengers, drew attention to the persuasiveness of this Court's reasoning in Peart [149].

3. Most matters of statutory interpretation are controversial by the time they reach this Court. However, the error made by the Privy Council in Slazengersis, with respect, quite basic. In beneficial legislation why should a definition of "injury" be narrowed because Parliament adds to it an extension for cases of disease said to be "included" within the definition? By the ordinary canons of statutory construction, the primary definition will stand undiminished. It was very properly conceded for the employer that the word "injury" appearing in its primary sense, would not be read down given the ambit of the Act. It can only be enlarged by the addition of certain disease cases. That will still leave other disease cases compensable if they fall within the primary definition because they involve an "injury" in the primary sense. For a very long time, before the statutory extension was added, the manifestations of certain diseases were accepted as "injuries". Workers' compensation legislation, which is protective of basic rights, should not be construed to narrow those rights unless a clear purpose to do so is evinced by Parliament. If compensation were rejected, it would undermine the principle of compensation law that every employer must take a worker as he or she is found. The mere existence of a longstanding condition, rendering the worker susceptible to injury (external or internal), is no disqualification, of itself, from compensation benefits.

4. Whilst it is true that the Court must avoid the unsettling effect of change and must normally pay heed to the interests of continuity and certainty in decisional authority [150], higher even than that duty is the Court's duty to the law. This Court has not withheld a fresh examination of legislation of widespread application (including workers' compensation legislation) where it is convinced that the law required that course. Hussey was itself such a case. That decision introduced a substantial alteration to what had then long been assumed to be the law. It occasioned amendment of the Act to restore what had, until then, been assumed to be its correct operation. If the law has become unclear and, in the Court's opinion, distorts the enacted purpose of Parliament, it is the duty of the Court to uphold the law as made by Parliament and as expressed in its chosen words. This is especially so, in a case such as the present, where the Court originally construed the purpose of Parliament in an accurate way only to be reversed by reasoning of the Privy Council which appears to have gone beyond the argument put to their Lordships by the successful appellant.

5. Whether to act or leave it to Parliament to correct an exposed error is a matter, in each case, for reflection and judgment. It is true that premium, re-insurance and other business decisions will have been made on the basis of the previous understanding of the law. But that was also the case before Slazengersand Hussey. Where that law has become distorted by error, this Court will hesitate to condone and perpetuate the error, particularly where doing so deprives persons of benefits, often crucial for sustenance, which a correct construction of the legislation provides.

6. So far as concerns the passage of the 1987 Act soon after Hockey was decided, I would answer in the terms used by Dixon CJ in R v Reynhoudt[151], cited by Toohey, McHugh and Gummow JJ. It might be different if the record showed that the particular point was considered and determined by Parliament one way or the other. In the present case there is no such suggestion. It is preferable to derive the modern canons of statutory construction from the realities of the legislative process rather than from mythology. To the extent that I said otherwise in Public Service Association v Industrial Commission [152] I was affected by the mythology, uninstructed by Reynhoudt, and I have now changed my mind.

Conclusion and orders

The result is that this Court should reject the reasoning adopted by the Privy Council in Slazengers. Subsequent authorities which have accepted that reasoning should be reconsidered. If leave is required, it should be given. No longer is there a dichotomy between "personal injury" in its full sense and "disease injury" within the additional part of the definition. A worker is entitled to succeed if he or she can bring a claim within either head of recovery. Logically, the first question to ask, including in cases which might otherwise be classified as manifestations of a "disease", is whether, notwithstanding that manifestation, the case falls within the primary definition of "injury" as a "personal injury arising out of or in the course of employment". In that context, the word "injury" should not be given a narrow meaning. It should have an ample application, in no way read down because Parliament, additionally, has provided a separate head of recovery for cases of work-related diseases It is not to the point to complain that this will lead to adventitious outcomes depending upon the nature of the precise "injury". That is inherent in the definitions contained in the 1987 Act. As Powell JA pointed out in the Court of Appeal, it has been a feature of workers' compensation law virtually since the first statute was enacted.

The approach to the definition of "injury" which I favour does not necessarily mean that every catastrophe connected with a progressive disease will fall within the definition of "personal injury", primarily so defined. Whether, in the case of a progressive disease, leading inevitably to a sudden or identifiable pathological change, it can be said that such change constitutes a "personal injury" can be left to determination on a case by case basis. It must be assumed that Parliament intended the extended definition, enacted to cover cases of "disease" within s4(b) of the 1987 Act, to have some operation.

Whatever may be that operation in other cases, the facts of the present case sustain the conclusion of Judge Thompson that the worker suffered a "personal injury". The sudden tear which caused the haemorrhage and the clot constituted a "personal injury". It was no less so because it was internal. It is enough that the "injury" took place in the course of the employment. It is not necessary to show that it arose "out of" such employment. The suggestion that it was necessary to establish a causal connection represented a judicial attempt to set back the clock to a time before Parliament made the phrase disjunctive. We should now renounce that attempt and return to the words of the statute as this Court explained them in Peart.

Whether, in the then state of this Court's authority, O'Neill[153], Ascione [154] and McIntosh [155] were correctly decided does not need to be determined in this appeal. Upon the proper application of the 1987 Act, as now determined by this Court, Judge Thompson was correct in the approach which he took on the evidence which he accepted. The Court of Appeal erred in disturbing that approach.

The appeal should be allowed with costs. The orders of the Court of Appeal should be set aside. In lieu of those orders it should be ordered that the employer's appeal to that Court be dismissed with costs.