Expert evidence
Expert evidence is used to provide information to the court, which is likely to be outside of the knowledge of the magistrates, judge or jury. Opinion evidence can be given if the expert is qualified to provide such an opinion.
Duty of an expert witness
An expert is under a duty to help the court by giving opinion which is objective and unbiased in relation to matters within their expertise. The duty is one which is owed to the court rather than the party who is providing the instructions.
The Criminal Procedure Rules require an expert to provide certain information such as any potential conflict, an appeal which has been allowed due to a deficiency in their evidence, convictions or adverse judicial comment.
Will an expert always be heard?
Applications can be made to exclude expert evidence if it is argued its prejudicial effect outweighs its probative value. The courts have also indicated a willingness to exclude the evidence if it is insufficiently helpful to a jury in reaching its conclusions. The court can also reject evidence, for example, if it decides that the witness has not properly established his independence or has not complied with his duty to the court.
We will not hesitate to challenge experts called to give evidence by the prosecution if there is a prospect of exclusion.
What types of expert are used in criminal cases?
There is a wide range of relevant expertise in criminal law. This could include forensics such as DNA and fingerprints or footwear marks, facial recognition where identification from a still or CCTV is in issue, medical experts in respect of injuries, psychiatric or psychological reports, autopsies or gait analysis.
How do you find an expert?
We have a register of tried and tested experts in every discipline. An expert witness is not just an expert in their field, they have additional skills such as report writing and experience of giving evidence in court.
It is important, therefore, to get the right witness for your case and we can do this for you.
How can we help?
If you need specialist advice in relation to any criminal investigation or prosecution, from the initial investigation through to court proceedings, please get in touch. Call John Howey on 020 7388 1658 or email jhowey@jfhlaw.co.uk. Let us help.
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DNA evidence as a reasonable doubt?
An article in the Guardian on 2nd October has highlighted some of the problems surrounding DNA evidence. Since it was first used to secure a conviction in 1986, DNA evidence has developed something of an unshakeable aura about it. It is common to hear in court ‘there is DNA evidence’ as if that somehow proves guilt beyond any doubt, let alone beyond a reasonable doubt.
Whilst science has developed to the extent that in many cases there is no doubt about who the DNA is from, what science cannot yet do is tell us how someone’s DNA found it’s way to a particular place. Some years ago, I defended in a burglary case, where the sole evidence against my client was a cigarette butt with his DNA on it found inside the burgled premises. That was sufficient for him to be charged and the case to proceed to trial. There was no evidence of the circumstances in which his DNA came to be on the cigarette butt or when and how the cigarette had found it’s way into the building. Fortunately, the District Judge trying the case recognised this and he was found not guilty, but both the police and the CPS thought they had the right man.
DNA evidence problems
Scientific developments have brought their own, fresh set of problems. Early DNA profiling was restricted in the profiles it could produce, as it required larger amounts of material for testing. Modern technology can develop a profile from smaller and smaller quantities of cellular material, and can often identify more than one person’s profile within a small sample. This gives rise to problems of cross-contamination, where one person’s DNA finds its way onto a second person, who then deposits the DNA at a different location; or cases where a DNA deposit is left at a location that becomes a crime scene later on.
DNA technology is clearly a vital tool for the police and prosecuting authorities, but there remains a need for caution when a case is substantially dependent on DNA evidence.
John Howey, Senior Solicitor
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