More questions for a forensic scientist to answer….

By Anna Sandiford 17/11/2011

Carrying on again from Grant’s post:

HappyEvilSlosh asked:

I’ve heard that in forensics often the scientist knows the details of the case and what side of case they are finding evidence for. Is this actually the case and if so don’t you think it would be better, in terms of determining the facts instead of achieving a verdict, to instead have some level of blinding between the forensics researchers and the investigators?

It is very difficult to provide any useful scientific advice or interpretation unless we know the framework in which the science sits. New Zealand has an adversarial legal system, which means each side puts forward its case and the court decides which to believe. One of the challenges of forensic science is to try to establish the facts of the case: either through crime scene examination, testing of items and/or interpreting the findings in terms of each side’s contentions. Having said that, we very rarely know the whole circumstances of a case, particularly in relation to lay witnesses.

The Crown employs its own experts through the Police contract with ESR so most ESR scientists pretty much only do work for the Police. They will always know when they have cases from the Police because of the necessary paperwork that accompanies items. They also attend scenes with the Police. It would therefore be impossible for ESR to provide scientific advice without knowing whether they are being instructed by the Crown or the Defence.

Expert witnesses are not there to provide the answer that suits their client; they are there for the benefit of the court. Of course that can be difficult if the information you are telling your instructing party does not support their case but that is how it has to be. We should not have an opinion on the verdict — that is the job of the court. However, some experts have trouble recognising that and sticking to it — it is the job of the court and the lawyers to ensure that experts remain as impartial as possible. If an expert is demonstrably advocating for a particular side or is demonstrating bias in a case then their impartiality should be challenged and their evidence potentially not accepted in court.

Some experts are routinely biased in their presentation of evidence in court and there is nothing that can be done to prevent that because of the type of evidence they give (I can’t give details because I don’t want to point fingers). However, I have seen the court address this by telling them to re-phrase their answers so as to be fair and not to use words such as ’victim’ or ’assailant’ because of the implications of their meanings; they should instead use words such as ’complainant’ and defendant’.

In terms of undertaking an investigation of findings by introducing some form of ‘blinding’ — that does exist in a way because, as indicated before, we as independent experts very rarely know all of the information in a case. How much is relayed to Crown experts informally by the investigators is not something on which I can comment.

I think that independent review of the work of forensic scientists is very helpful in identifying bias and/or keeping experts (both Crown and independent) mindful of the fact that their work may be reviewed by someone outside their own organisation. This could be through some formal accreditation process (as used to be the case in the UK with the Council for the Registration of Forensic Practitioners and the processes coming through with the Forensic Science Regulator) or by independent experts reviewing Crown work and, potentially, vice versa.

In any event, full, fair, accurate and transparent reporting is vital for helping to minimise the risk of scientific bias.


Michael Edmonds asked:

Already have the book but am curious to ask –
If you were accused of a crime, which country in the world would you rather be tried in (i.e. which do you think has the fairest justice system?). I was going to specify that the person would be innocent, but forgot to add that before I posted.

In the days of the Forensic Science Service, personally, I would have preferred to be tried in England. I am lucky in that I know how the adversarial system works and who to ask to help review a case. Most people aren’t as lucky as me but I think England has one of the best review systems going — transparency and conferring of experts from opposite sides has been a common occurrence for some time now; less so in New Zealand and Australia. Given that many states in the US still have the death penalty, I wouldn’t want to be there.

As for inquisitorial systems, such as those that operate in mainland Europe and Scandinavia, I’m not so sure. Although I don’t know much about them and in theory they are good, I met a fingerprint expert from Finland last year and he had never given evidence in his entire 20 year career. Personally, I’d like to think that my experts knew what a court was like — attending court and giving evidence hammers home the significance of the work you’re doing; it will probably change the lives of many people so it has to be given the appropriate gravity and seriousness it deserves and there’s nothing like giving evidence in court to make that point.