J. Forens. Sci. SOC. (1 9 74),14, 183

The Presentation of Scientific Evidence in Court-Great Britain

A. R. BROWNLIE Solicitor Supreme Courts, Edinburgh, Scotland

This paper, delivered at the Spring Meeting of the Forensic Science Society held a t Lyon on May II, 2973, pre~ents a simple outline of the place of scientific evidence in the Courts of Great Britain and draws attention to the dzferent emphasis in the use of scientijic evidence necessitated by the French judicial system.

( A short report of the Society's Spring Meeting held at Lyon on May II, 1973, together with "The Investigation of Road Traf ic Accidents" by A. K . Mant, was published in Bulletin de MCdecine LCgale et de Toxicologie MCdicale (1973), 16, 4 . )

Differences within Great Britain-Two Legal Systems Before discussing scientific evidence in the Courts of Great Britain it is

necessary . to say . something about the judicial system under which such evidence comes to be given.

Great Britain of course comprises two separate legal jurisdictions: England and Wales which enjoy a system based upon their native common law in- fluenced by Norman French law but totally unaffected by the Continental system which developed from the Code Napoleon in the early 19th century.

Scotland on the other hand still retains the system of law which it has enjoyed since before the Union of the Crowns. In fact the Treaty of Union ( I 706) by which the Crowns of Scotland and England were united specifically provided in Articles 18 and 19 that while the Kingdoms should be united and while the English Parliament should come to an end and be supplanted by a new British Parliament, Scotland should retain her ancient system of law and her own Courts as she does to this day.

Before commenting therefore upon any of the differences between the legal systems of Great Britain and of France I must make it clear that there are fairly important differences between the two legal systems within the United Kingdom-those of England and of Scotland. In addition to numerous sub- stantive differences of the rules of law particularly for example in regard to land law, in regard to the law of husband and wife, in regard to criminal law and to some extent in regard to the law of evidence, there are fundamental differences of approach which can be explained by the different origins of the two systems and the different spirit which has guided their development. Briefly the legal system of England is based upon the ancient common law of England which was evolved by their judges and by the custom of the realm over several centuries-the system which has spread to many colonial and dominion possessions and even to parts of the United States of America so that English legal ideas have proved of great influence in these lands. The English system is a system which looks always to stare decisis; i.e. thc Courts on encountering a problem look to see what they decided the last time they encountered a similar problem: they are relatively unconcerned whether their decisions form a connected and coherent body of principle. By contrast the law of Scotland has developed with many contacts in the 13th and 14th century with the laws of the trading nations of Europe. In these times there was much communication with the Low Countries: many Scottish students went to study at the great Universities of Leyden, Utrecht, Paris, Padua and Bologna. Roman law played

a great part in the formation of legal ideas and there was and still is a measure of common thinking, say, between Scots law and Dutch law. But the ideas thus promoted were systematized by a handful of great Scots legal writers in the 17th and 18th centuries and these writers did such a good job of describing the principles of law that the Scottish system has not had to concern itself with what the Courts decided last time, so much as with the underlying principle which the Courts would then identify and proceed to apply to the circumstances of each case. Scots law has therefore developed as a system based on principle whereas English law has developed as a system based on precedent.

I t is interesting that at a time when Great Britain with its two systems of law has entered the Common Market, Scots law is almost certainly going to be found more in line with the legal thinking of the European Economic Com- munity than English law, though of course English law because of its world- wide influence is expected to be well able to hold its own. Scots lawyers are delighted that one of the United Kingdom judges appointed to the Court of the European Community at Luxembourg is a Scotsman, Lord Mackenzie Stuart.

For the purposes of this paper however I want to emphasize not the differ- ences between Scottish and English law but the great similarity of their out- look in regard to the purpose and the conduct of both civil and criminal Court proceedings.

Differences within Great Britain: Civil and Criminal Law In Great Britain there is the further division between criminal law and

civil law (by which I mean the law which regulates the private rights of in- dividuals). These are always kept separate. If I drive my motor car recklessly into another car and injure the driver of the other car the consequences are twofold. First I may be prosecuted in a criminal Court for my reckless driving and punished. But secondly I may have to face a claim from the injured driver for damages for the personal injuries which he suffered because of my bad driving, and also for the cost of making good the damage done to his vehicle. These two matters are separate: they may give rise to two separate cases-one a criminal prosecution and the other an action for damages in a civil Court. Witnesses may have to give evidence twice to describe what happened in the accident. I t is true of course that if I plead guilty to the criminal driving charge this may be used against me in the civil Court, for I have made a judicial admission of my fault. But the two matters remain fundamentally distinct.

It is not so in France and I am aware that it is quite normal for the civil party to be joined to the French criminal case and for his claim to be assessed in the same Court process.

Suspicion, Detection and Proof There is another way in which the British systems and the French systems

differ and that is in criminal enquiries when the process of suspicion, investiga- tion and elimination of suspects is dealt with. In Great Britain the enquiries into a crime are made by the police without any direct control by the Courts although in England the judges have pronounced a set of 'yudges' Rules" which are supposed to guide the police in interrogating suspects. The res- ponsibility for investigating these matters lies with the police and they carry out their task quietly and generally without publicity. Only when they have satisfied themselves that they have found the party responsible for a crime do they place the facts before the authorities and a criminal prosecution is com- menced. The police of course have to take note of the fact that the evidence which led them to suspect a certain person may and probably will be little use when it comes to proving guilt in a Court of law. In France the matter, if serious, comes at an early stage into the hands of the Courts and ajuge d'instruc- tion takes charge of the case, building up a dossier on the suspect, carrying out examination and enquiry publicly in a judicial fashion, and eventually passing the case for trial when the President of the Court undertakes the examination

of the suspect based on his dossier, and the conduct of the case against him (Hamson, I 955; Vouin, 1966). I t seems remarkable to French observers that in Great Britain the police are allowed to prepare a case against a person, unknown it may be to the suspect, and without any possibility of the suspect checking on or sometimes even knowing what they are doing. To British eyes the French procedure whereby the suspect is publicly examined by the juge d'instruction, though with his own counsel present throughout, savours of the beginnings of a trial when the case has not yet crystallized against the accused. To British eyes it is hard to understand how in France the judicial machinery is integrated with the machinery of investigation and detection.

We have heard how in France this procedure of investigation goes ahead under the control of the juge d'instruction and how eventually if he is satisfied (and this is no empty formality) the matter may become a full-scale trial of the accused. At that stage scientific evidence, if it is to be presented to the Court, would probably be presented by a specially appointed Court expert selected from the Court list who would give his evidence based upon his privileged examination of the clothes or the documents or the materials which had been furnished to him by the police. Although it is possible for the de- fending Counsel to introduce scientific evidence from a witness of his own choice, such a witness in the normal way, unless a man of special stature, would probably in France not enjoy the same regard as the official witness chosen by the Court as their expert witness. Defence scientific evidence in France tends therefore to be less effective than similar prosecution evidence.

The Scientist as a Witness The situation is different in Great Britain. Because the trial of a criminal

case in Britain is conducted on a partisan basis, each side preparing its own case, the services of a specialist witness may be invoked either by the prosecution or by the defence. I t is not the custom for the Courts in Britain to maintain lists of approved witnesses (except perhaps in the very specialized matter of medical witnesses qualified to examine and report on cases where a marriage is to be annulled for reasons of non-consummation) and in the average case it is quite possible that the prosecution may instruct and call upon an expert to give evidence who may the following day be giving his services to the defence in another case. On the other hand the defence are at liberty to employ and call upon whoever they wish to assist them by giving expert evidence subject only to considerations of cost. Many Court cases and a high proportion of criminal cases are nowadays litigated with the assistance of legal aid in Britain (that is to say they are paid for out of public funds either wholly or in part) and given time there is generally no difficulty in getting legal aid for the services of an expert witness of sufficient competence at a reasonable fee pro- vided the client can show a good reason why he requires to employ such a witness.

The general rule in Britain is that witnesses give their evidence personally on oath from the witness box. Indeed in Scotland where it is necessary for all evidence to be corroborated where it forms the main strands in a case, it is not unusual for experts to hunt in pairs, although this is not strictly essential SO

far as their evidence is expert evidence, since the need for corroboration does not apply to opinion evidence. Invariably however a report such as a post- mortem report deals not only with opinions but also with the factual structure on which the opinions are based, and it may be that the Scottish habit of having two witnesses even to opinion reports is necessary to ensure that the factual basis of such reports is adequately established.

Although I have indicated that it is possible for both the prosecution and the defence to employ experts to give scientific evidence in criminal or in civil cases in Britain, it is in practice often difficult at short notice to find the right expert, a man who has a wide knowledge of a particular subject and who at the same time is accustomed to appearing in Court and being questioned about

his statements. This is one of the advantages for a lawyer like myself of being a member of such a Society as the Forensic Science Society because in so doing he becomes aware of who the specialists are and whom he should approach to obtain evidence of a skilled kind upon this or that subject of science or medicine. Generally speaking the evidence which the expert witness is asked to give is related to facts or materials in a case. I t might be for instance that in a drunk driving case the accused person wished to have an analysis of a blood specimen taken by the police at the time of a motoring offence; or a man accused of murder might wish to argue that at the time of the offence his mental condition was such that he did not know what he was doing. Then a psychiatric examination would be necessary. Or a witness may be asked to examine stains and decide whether they are of human blood or not. In the Crippen case (Young, 1920) expert evidence was given in England about a piece of flesh from the abdominal wall of a woman and whether the scars on it could have been the result of an operation for hysterectomy. Generally speaking in Britain facilities are readily enough accorded by the prosecution for the defence expert to make his enquiries and examination and generally speaking the accused has every right to see and examine the exhibits or productions (Davies, 1973). Occasionally it is possible for the defence specialist to be present when the prosecution expert is making his examination, and where this can be done both experts normally reach a similar conclusion. Some experiments of course involve destruction of the material upon which they are carried out and in such cases where there is insufficient material the defence expert cannot carry out his experimental work. In many cases the defence expert is not consulted or at any rate does not come into the picture until long after the items of real evidence have been disposed of or are perished or lost. And in these circum- stances all that he can do is to give his opinion in a general way and perhaps to raise doubts about or criticise the methods used by the prosecution specialist. His evidence in such cases may accordingly be weakened.

In Britain (or more accurately I should say in England) there is a series of Forensic Science Laboratories set up and paid for by the Government (Curry, 1964). These laboratories contain a number of scientists skilled in various sciences who undertake work mainly for the police in their district on a wide variety of subjects. I t is interesting that rhese laboratories since their inception around I 935 have regarded themselves as interested merely in the ascertainment of the truth and they are equally as available to the defence as they are to the prosecution, though naturally one laboratory will not supply scientific help both to the prosecution and to the defence at the same time. I t has always amazed me that the defence facilities of these laboratories are not more sought after by individuals who face serious criminal charges.

How is Evidence Given? I should think that in most cases in Britain where scientific evidence is given

it first takes the form of a written report made by the prosecution or the defence specialist to the prosecution or the defence legal advisers. If they decide to use the evidence in Court they will normally have to call the expert who wrote the report to give evidence personally at the trial of the case. There are a number of ways in which evidence, especially where it is routine or formal evidence, can be given in the form of a written certificate or affidavit, but it is still true to say I think that the main and certainly the most satisfactory method by which the expert's findings are transmitted to the Court is by oral evidence given by the expert personally from the witness box. In such circumstances the expert is sworn to give his evidence as a witness for the party who employed him. This does not mean that the expert will bend the truth or twist the facts because he is giving evidence as a witness for one side or the other. He will give his evidence to the best of his ability as a scientist reporting upon an enquiry or an examina- tion or an experiment. British Courts rely very considerably upon cross examina- tion as a means of showing whether evidence is reliable, or whether it is unfair

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or overstated or misconceived or even frankly lying. I know that many scientists are unhappy about the application of the traditional methods of minute questioning to the giving of scientific evidence. I believe that in Germany for example a scientific witness is allowed to give the whole of his evidence in narrative form so that he provides a connected narrative of what he has done and only at the end may he be questioned upon aspects of it (Coutts, 1966). Where the British cross examiner only partially understands the subject on which he is posing questions I agree that the result can be unfortunate, but where a witness is cross examined by a fair though searching cross examination from a Counsel who knows that he is talking about the result can I believe be most helpful to a Court in showing whether the evidence of the witness was fair, reliable and trustworthy.

Increasingly I think evidence of a complex or detailed kind is given both in Scotland and especially in England in the form of a prepared written report. The English courts in recent years have advocated the exchange between opposing medical experts of their medical reports at an early stage in repara- tion cases so that each expert can gauge where the area of disagreement lies between his evidence and that of his opposite number. This practice has led I believe to many cases being shortened. When the specialists see how close their reports are to one another they at once identify the area of disagreement; and this having been done they are generally half way to resolving the apparent differences. Two days ago I was discussing this very point with one of the London lawyers for one of the largest insurance companies in England. He told me that this rule alone of the Civil Evidence Act 1972 that medical reports must be exchanged at an early stage in litigation is having a widespread effect in encouraging solicitors to be more open with one another about the whole process of litigation, and tending to put an end to some extent to the practice described in the English idiom of "playing your cards close to your chest".

In Britain the evidence of the expert is not supposed of itself to decide the case. It is intended to provide the Court with the material necessary to enable the Court to come to a reasoned and independent decision on the merits of the scientific issue. Occasionally in Britain persons of skill may be called upon to report on a remit from the Court on a particular matter, but there is no place in either England or Scotland for a scientific expert'se (Ploscowe, 1935). Very occasionally the skilled witness may be directed or permitted to experiment in Court or in private and may testify to the results which may even be produced for the Court to examine, but the Court should not be asked to handle scientific instruments. In the Crippen murder trial for instance the jury were invited to peer into microscopes to decide for themselves whether the marks on fragments of abdominal skin were operation scars (Young, 1920). I t is most unlikely that this would be permitted to a modern jury. Greatly enlarged photographs are often used to assist in explaining scientific evidence and I have seen charts, models and blackboards used in Courts especially in complex accident cases: and at a recent meeting of this Society we were told of an English ~rovincial Court specially fitted with projector and screen for the giving of police traffic accident reports in this way. Such aids would certainly be used for example in the investigation into the cause of the crash of the Trident aircraft, Papa-India, the report of which has just been published (Civil Aircraft Accident Report - 3 1 d l -

Recently in Edinburgh we have had one experiment in the case of closed- circuit television cameras in Court. I think this was found to be only moderately successful. A good many months ago there was a disaster in Clarkston Glasgow caused by the accidental explosion of an accumulation of domestic gas which had leaked into a long air space beneath a row of shops. At the Fatal Accidents Enquiry which followed that disaster the many hundreds of photographs which had been taken were very clearly shown to the large number of solicitors and counsel involved by the use of closed-circuit television cameras.

The Effect of Scientific Evidence Scientific evidence carries no special weight just because it is scientific and

may be challenged disbelieved or rejected just like any other evidence (Cooper, 1953). I t may on its own occasionally be sufficient to ensure a criminal con- viction, but it is more usual to find it embedded in other evidence ofthe actings and sayings of other witnesses.

Since the expert witness is merely contributing another item to the whole body of evidence to prove or disprove a case, and is not himself deciding the case, it is not proper for the whole point at issue to be put to the expert witness (G. u. G., 1924). I t is in order for the expert to testify that the bloodstains on the knife in the accused's hand are of the same blood group as the blood of the stabbed victim-but it is not proper for the expert to answer the whole question "did the accused murder the victim?"-because that is the province of the Court, of the judge and jury.

Scientific evidence ought to be understood by the Court at least in outline, and every effort should be made towards this end. In 1967 with the introduction of the Road Safety Act with its "Alcotest" device for breath tests and the taking of virtually compulsory blood or urine samples, the analysis of microquantities of blood began to be done by gas chromatography. In an early case in which I was questioning the analyst about the apparatus the judge, a lady, became impatient and said to me "Mr. Brownlie, do you want to see the blueprint of this machine", to which of course I could only reply "Yes. That is exactly what I want." If the Court does not try to understand and evaluate the evidence of the scientist the Court is failing in its duty. I remember once hearing a criminal case in which a motorist had been caught in a radar speed trap. The evidence of the police was so brief and obscure that the police witness was really only saying 'I have a magic black box. If a motorist passes my box it tells me how fast he is travelling." That is not good evidence, and it is certainly not scientific evidence. And yet no higher standard of accuracy is demanded of a scientific witness than of an ordinary witness (Moulton, 191 I ) . The law does not require proof beyond all possibility of error (Ardwall, I 909). TO do so would be to exclude human evidence altogether. Even scientific testimony can offer certainty only within the limits of human experience.

In Britain the general rule is that in civil cases the standard of proof is according to balance of probabilities. That is to say a fact is proved if the evidence for it is more likely to be true than the evidence against it. But in criminal cases the standard of proof is a higher standard. The case is only proved where all substantial doubts have been removed, and where the case is established beyond reasonable doubt. Scientists have rightly criticized these concepts and have sought to quantify them in a more precise way (Walls, 1972) but the reply of the law remains in the words of Sir James Fitzjames Stephen, ' 6 To attempt to give a specific meaning to the phrase 'reasonable doubt' is trying to count what is not number and to measure what is not space" (Abra- hams, 1958). In Britain at any rate the Courts are hardly yet able to cope with mathematical evidence of probability, although the beginnings of such evidence are to be found for example in the evidence given of blood genotypes in disputed paternity cases where the likely occurrence of a particular combination of blood factors in a population may be mathematically expressed. I t seems likely that some progress may be made in the future in the direction of a better apprecia- tion of probability evidence in suitable cases.

Some Problems There is no doubt that the part to be played by scientific evidence in our

Courts is increasing. This fact tends to emphasize the problems which surround the giving of expert evidence. I have time to mention only one or two of these.

The first I have already touched upon. I t is essential that the evidence be expressed in terms which the Court and the litigants can understand. There is a 1angua;;e of science which is not easy for those trained in other disciplines to

follow. There are professional barriers between .the professions of science and the law and there is no doubt misunderstanding by each profession of the methods and aims of the other.

I have spoken of the difficulty inherent in the French system of having an official Court expert in that the defence expert is inevitably regarded as merely an ordinary witness possibly of small credit. Nor does the French system dispose of the difficulty of a clash of experts. The case of Marie Besnard perhaps illustrates the problem of the supplanting of one expert by another taken to extremes (Folliot, 1963). While the succession of experts criticized one an- other's toxicology the accused Marie Besnard who was alleged to have poisoned her husband and other relatives languished for twelve years in uncertainty and doubt. I t would be unfair to criticize the French legal system on the basis of a single case which I do not fully understand, and a well known and scandalous case at that, but it is obvious that there is a problem here.

In British law in particular the absurdity of referring the resollition of two conflicting experts' views to the untrained jury who are generally innocent of scientific knowledge is apparent, and yet in my experience results are generally acceptable.

Finally there is some irony in the fact that on the one hand as Dr. Hamish Walls has written "the Courts want to hear authority issue from the lips of their expert witnesses" (Walls, 1972). On the other hand scientists are keenly aware that the true business of science is the formulation and testing of hypo- theses about the physical world, and while no hypothesis can be finally proved it is always open to disproof by the discovery of a single fact inconsistent with it. Scientists are therefore keenly aware of the tentative nature of their con- clusions.

And there is a final difficulty. The prosecution can usually find the experts they require, for their resources are greater and time is on their side. But for the defence it becomes increasingly difficult to locate in the time available the right expert who has the knowledge and ability to provide comparable facilities to the defence (and these are becoming more and more sophisticated) to those which are available to the prosecution. This is because in some specializations there simply are no private specialists who are prepared to give expert evidence -a problem which I should imagine is at least as acute in France as it is in Britain. Let us hope that the opening up of the frontiers and the great adventure of the European Economic Community (of which perhaps this visit is one of the minor first-fruits) may eventually improve the availability and inter- changeability of skilled witnesses in every field in which their specialist know- ledge could help to further the ends of justice.

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