Stories concerning expert witnesses have not been off the front pages of newspapers for over 30 years as miscarriages of justice and the collapse of high profile trials have been reported. These include the overturned convictions of Judith Ward and the Birmingham Six and more recently Stefan Kiszko, Sally Clark, and Sion Jenkins. More recently we read press reports of the collapse of the multi-million pound trial of champion jockey Kieran Fallon and five others have focused on the prosecution’s use of an expert witness. We have seen one Home Office pathologist banned from court work for 3 years and another resign from the Home Office register following the upholding of 20 disciplinary charges by the Advisory Board for forensic Pathology.


This does give problems for investigators as reliance has to be placed on experts to provide evidence in many cases, from homicide to road traffic collisions to frauds. The cases highlight the importance of an investigator’s decisions in selecting and using expert witnesses. Failed cases demonstrate not only difficulties with their scientific expertise but their compliance with rules on disclosure.

In this article we will seek to assist investigators by explaining the law relating to expert witnesses and what issues investigators need to consider when making important decisions about selection and use of experts.

It has been recognised by the courts for more than 400 years that there are areas of knowledge which the court or jury need assistance in understanding. This is the reason why experts in their field are permitted to give evidence of opinion as well as fact. Because of this privilege the use of experts is, or should be, strictly controlled by the courts and there is a body of law, rules and guidance with which the investigator should be familiar. The decision as to whether a person is an expert is a matter for the trial judge. There may be a problem with this as research conducted by the City University, London indicates that three out of four judges and lawyers fail to check the qualifications of expert witnesses. Late discovery of the inadequacy of an expert witness may be fatal to the case.

So, how do people become expert witnesses? Experts can become ‘experts’ by several routes. The first, and most obvious, is by formal education and qualification; this can then be reinforced by practical experience. A good example of this course is a forensic scientist who perhaps obtains a science degree at university and then undergoes further training and gains years of practical experience before being allowed to give evidence in a criminal court. Another route may be by training which does not necessarily involve a formal academic qualification. In recent years the expertise of road collision investigators has been recognised and accepted by the courts. In R v Murphy [1980] 1 QB 434 a police constable who was a traffic collision examiner was allowed to give his opinion as to the nature of a collision, the course of one of the vehicles involved and other matters said to be deducible from marks on the road and damage to the vehicles. The Court of Appeal upheld the trial judge’s ruling. Provided the judge was satisfied that these matters were within the officer’s expertise, his evidence was admissible.

It is also possible that experience alone in a particular field may be accepted by the courts, as may occur when considering the provenance of works of art or antiques.

A more unusual route is the expert ad hoc. This is a person who is held to be an expert and therefore give an opinion on a single incident. In R v Clare and Peach [1995] 2 Cr App R 333 a police constable had spent many hours studying video recordings of people arriving at a football match and later scenes of disorder in a town centre. He was permitted to give evidence identifying the defendants as people shown on the film committing offences. This was approved by the Court of Appeal on the grounds that as a result of studying the film at length the officer had special knowledge which the jury did not possess. This is particularly relevant now that the product of intrusive surveillance is more frequently used in court.

The most important element for investigators and the experts they employ is that the expert must be independent. The duty of experts is to the court, not the party that engaged them and paid their fee. The courts have come down hard on experts who have forgotten where their duty lay and favoured those instructing them. There are potential difficulties, particularly in long-running investigations where a forensic scientist, or other expert, engaged to advise can come to be seen as part of the team and could be in danger of losing their objectivity.

The purpose of having an expert is to give an opinion on matters in of which the court does not have sufficient knowledge. This will include science, DNA, medicine, pathology, accountancy and many other areas. On the other hand there are a number of areas where the courts have decided that expert evidence is not required and therefore cannot be called.

For example leave would not be granted to call a professor of psychology to demonstrate the likely deterioration of the memory of an ordinary witness. (R v Browning [1995] Crim LR 227) Nor could an expert be called to give an opinion on whether an unidentified person in a photograph is under the age of 16 (R v Land [1998] 1 Cr App R 301). It is usually the defence who try to bring in experts to persuade juries not to trust their own judgement. In R v Masih [1986] Crim LR 395 the defendant was accused of rape. He had no psychiatric illness but had an IQ of 72 which is above sub-normal but only just. His counsel, sought to call expert psychiatric evidence about his client’s ability to appreciate the situation and recognise whether or not the victim consented. Because he had no mental illness and was not sub-normal the trial judge would not admit the evidence and the Court of Appeal agreed. It was a matter for the jury and within their experience.

In R v Turner [1975] QB 834 the defendant was tried for battering a 15 year-old-girl to death with a hammer. He claimed that he had been provoked when she told him that the baby she was carrying was not his and that she had been prostituting herself while he had been in prison. He tried to call a psychiatrist who would say that he was truthful and that he had had a deep emotional relationship with the girl and this was likely to have caused him to fly into a blind rage. The evidence was not admitted by the trial judge and his decision was upheld by the Court of Appeal because there was nothing that was not in the experience of the jury and no expert help was required.

An investigator should think very carefully before engaging an expert. The difficulty arises because once you have an expert’s opinion on any matter it will have a lot of influence on the decision to prosecute and subsequently on the jury. Once the decision to consult an expert has been made it is important that care is taken to instruct an appropriate person. Any lack of care in choosing and instructing an expert means an inquiry may be left with unhelpful or misleading opinion.

It is also essential that the questions asked of the expert are precisely phrased. Because you have an expert, the defence will have their expert to give a possibly contrary opinion. You may then have a battle of experts in the court on something that is only a very minor issue but it diverts attention away from the main evidence in the case and can seriously muddy the waters and mislead the jury.

So, as an investigator, and despite all of this you need some expert assistance. What are the issues you need to consider?

The first, and one of the most important decisions, is which expert to engage. There are a number of sources of help; primarily investigators should consider the database of expert advisers maintained by the National Policing Improvement Agency. The individuals on this list are referred to as ‘advisers’ rather than ‘witnesses’ as their role is very often limited to supporting an investigation rather than giving evidence in court. However, it is always a possibility that an adviser will actually become a witness. The NPIA (now the College of Policing) receive recommendations for the database from a number of sources. These include existing experts and investigators who have worked with the person in the past. Inspector Mark Britt from the College’s specialist operations centre says, “We also proactively seek out individuals with a particular expertise when we recognise that there is a demand that we cannot meet”. An example of this is medical doctors with specialist knowledge of head trauma in children. Inspector Britt can cite numerous examples of cases where expert evidence has been vital, as well as unusual areas of knowledge.

In a recent attempted murder case the hospital doctor initially examining the victim of a stab wound described the injury as ‘superficial’. The investigators were put in touch with a medical illustrator by the (then)  NPIA. This expert examined the forensic scientist report which stated that the knife used bore traces of fatty deposits. Using this as well as photographs, the illustrator was able to explain and demonstrate that the knife had penetrated much more deeply than was first thought and that the victim was extremely lucky to have survived.

The College of Policing does not accredit or recommend experts. They also publish a handbook ‘Practice Advice On The Management Of Expert Advisers’. A 2011 version of this is now available and is a must read for investigators contemplating the use of an expert.

The College is not the only register. There are a number of commercial organisations, such as UK Register of Expert Witnesses who have some 2,600 potential experts listed on their database. The advantage of this source is that virtually all of it’s members are subject to a vetting process. Lawyers who have previously utilised the expert are contacted and asked for their opinion about the expert in a variety of areas such as report writing and courtroom skills. The UK Register also supports it’s members by providing them with advice and support in relation to legal updates.

Once you have a potential candidate in mind, make absolutely certain that the person is a genuine expert. This may seem a strange point to make but do not forget the case of Gene Morrison from Greater Manchester, who used sham degrees from a fake university in the USA to help him get the work He claimed to offer 20 years’ experience in forensic science, psychological examinations, lie detecting, fingerprinting, surveillance and handwriting analysis. Mr Morrison is now serving a term of imprisonment for fraud. He gave expert reports and evidence in hundreds of cases before he was discovered. If you are thinking of using an expert, other than from the Forensic Science Service or LGC, do not be afraid or embarrassed about asking for references including sight of any relevant qualifications. It is a good idea to speak to any officers who have previously made use of the expert.

You must also be sure that he is an expert in the precise area you require. At the Old Bailey last year in a trial for alleged horse race fixing it emerged in cross examination that an expert from Australia called by the prosecution was not familiar with the rules or culture of British racing. This led to the judge stopping the trial and ordering an acquittal.

Once you have a list of potential experts available to you there are a number of important issues to consider before making your final choice. An individual might be supremely qualified in his particular field but his alone would not automatically make him suitable for use in your investigation. However well qualified in his specialism, unless he has received training on how to be an expert witness, he may not be best placed to advise and present his evidence in court. For example, is he aware of the duties of an expert witness, of the rules of disclosure and the need for impartiality? In the context of expert witnesses he who pays the piper does not call the tune – the expert’s duty is to the court. Despite the majority of the publicity being about misleading statistical evidence Sally Clarke’s conviction for murdering her children was quashed solely because of a failure by the Home Office Pathologist to reveal to the prosecutor the results of some tests he had carried out. The Prosecution are obliged to disclose any expert’s reports they obtain, whether they intend to use them or not. Unfortunately the same does not apply to the defence. They only need to disclose any reports on which they intend to rely. Any others obtained – perhaps with findings which might support the prosecution – do not need to be disclosed.

The fees charged by experts may vary considerably and can be a contentious issue. It is important to establish at a very early stage what the expert proposes to charge. Many experts will quote an hourly rate: investigator should ask exactly what the fee will cover. For example if an agreement is made for a set number of hours work, does this include writing the report an attendance at conferences There are dangers in setting a fixed number of hours; what will happen if the work has not been completed within that time? Is there a likelihood of further costs for scientific tests or examination? If these areas are not clarified when making the agreement the expenditure can very quickly spiral. There is no set guide to what an expert charges. The fee will depend on a variety of factors such as their eminence in their chosen field and rarity of their particular expertise. The UK Register of Expert Witnesses periodically surveys members about their hourly rates. There is a wide difference depending on the professional group. For example medical experts charged an average of £1,163 per day for appearing in court whilst scientist’s fees were an average of £720 per day.

Another often overlooked area is that of confidentiality. Most professional expert witnesses would never countenance speaking publicly about a case they have been involved in without the permission of the senior investigator. However if your case is a high profile one you may not wish to appear in someone else’s memoirs.

Rather than rely on verbal agreements it is advisable to prepare a written contract which clearly covers areas including costs and confidentiality.

Once engaged then the expert should be provided with a copy of the College of Policing  guidance titled ‘Guidance for Expert Advisers’. This sets out in detail the experts obligations and ensures that they are familiar with their duties.

Once the expert is selected then the investigator must clearly request what is expected. The expert will answer whatever questions are set so there must be careful thought applied to this. All decisions need to be recorded in a policy log. A careful record needs to be kept of all materials supplied to the expert to guard against allegations of selective briefing.

Annexe K of The Crown Prosecution Service disclosure manual gives detailed guidance as to how experts must certify that they are familiar with their obligations, prepare a disclosure index and reveal any potential issues such as convictions or adverse findings by professional bodies which may affect their credibility. The manual can be found on the CPS website.

The law relating to use of expert advisers has recently been included in the Criminal Procedure Rules. These can be found on the website of the Ministry of Justice. These set out the expert’s duties and importantly the contents of the report. This must include such areas as the expert’s qualifications, who carried out any tests and the conclusions. Importantly the expert will also need to disclose any issues that might affect his competence as a witness such as convictions or professional disciplinary findings.

Although there are many instances of experts giving excellent support to the prosecution there have been numerous high profile failures. Perhaps use of experts ranks alongside failures in the disclosure of unused material as the most perilous area for an investigator. When the training for Senior Investigating Officers was recently updated for the Professionalising The Investigation Programme the time dedicated to forensic science was reduced from four days to half a day. Nowhere in the process is there any input on use of experts. Perhaps it is time to look again at this situation.

The authors of this article, Graham Gooch and Mick Turner are former detective superintendents who lecture on behalf of Sancus Solutions on the use of expert witnesses for investigators.

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