Anna Sandiford: Credibility key for expert witnesses

The accuracy of science in a court case is paramount. Photo / Greg Bowker
The accuracy of science in a court case is paramount. Photo / Greg Bowker

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"A lack of accreditation of expert witnesses means that anyone with a scientific background and sufficient 'brass neck' could set themselves up as a forensic science expert and mislead the court."

So warns Lord Justice Leveson, an English Court of Appeal Judge. It has already happened: Gene Morrison. Originally jailed for five years on various offences after he masqueraded as a forensic scientist for many years, he is now imprisoned for an indeterminate period for child sex offences. OK, so he's an extreme example, but who is checking the standard of forensic scientists and the science they are presenting in court?

Many will say that the court itself is the place for establishing whether or not a scientist and their report is appropriate for a given case.

However, is that a good use of court time? If it is, who should be making that judgement? Can we realistically expect lawyers to be able to tell whether the science in a case is appropriate?

The whole point of expert witnesses is to provide information to the court that is outside the general knowledge of the triers of fact: the judge and jury. Unless they have a working knowledge of, for example, mixed DNA profiles in a sample being separated using a combination of LCN, Y-STR and SGM+, how are they to know that what is being presented is full, fair and accurate?

And that's before we even get to see what is in the scientist's casefile. There is often information in the casefile that is hugely informative but this information is not made available - it has to be requested. If you don't know what to ask for, you won't get what you need.

An article in the December 2010 issue of North & South is entitled "Guilty until proven innocent". The article describes three examples of miscarriages of justice in New Zealand. An extract from that article reads, "The three cases examined in this story exhibit some of the classic traits of miscarriages of justice worldwide: police tunnel vision, withholding of evidence, false witness identification or memory, incorrect or overemphasised expert evidence and poor legal representation."

As an expert witness working in the independent sector, it is my job to look at scientific evidence to see if it is incorrect or overemphasised or even if there is something that hasn't previously been considered for a variety of reasons.

In some cases, there's nothing of concern with the science. In others, the issues relate to scientific results that are in the casefiles but not immediately apparent in the reports. In other cases, it's scientific methodology. For yet others, it could be that the defendant wants his account of events to be considered but this hasn't previously been presented to the Crown's experts. There are many reasons.

I am passionate about accuracy and fairness of science in the courtroom; if we use science as part of a case to convict someone of a crime then that science must be correctly reported. It is not the job of an expert witness to have an opinion on whether or not the defendant is guilty; that is the job of the court.

Although accreditation of individual expert witnesses alone will not solve all the issues of incorrect or overemphasised expert evidence, it is a start and, in my opinion, should form at least part of the standards for allowing people to give evidence in court as expert witnesses.

Dr Anna Sandiford is a forensic science consultant and expert witness. View her work and that of 35 other scientists and science writers at Sciblogs, New Zealand's largest science blogging network.

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