When the science changes in such as way as to lower the validity of the original conclusion, should the forensic scientist be proactive in declaring this to impacted parties (as opposed to leaving it to defence lawyers to discover and act upon as they see fit)?

Well, Gary Bowering, my take on it is that the forensic scientist absolutely has a duty to advise the court when something affects their interpretation so as to alter their overall conclusions. In fact, there is a standard phrase that we put in all our reports that runs something along the lines of “My opinion has been prepared on the basis of information provided to me. If such information should change or additional information becomes available it may be necessary for me to revise my findings and conclusions.”

At the end of the day, lawyers are there to deal with the law; forensic scientists are there to deal with the science and it shouldn’t be left to defence lawyers (or prosecutors, come to that) to dig around to see if, on the off-chance, they can find anything amiss with the other side’s expert’s work.  One of the basic rules of examining witnesses is never to ask a question to which you don’t know the answer.

Many times I hear lawyers say how they hated science at school and how having to deal with forensic scientists makes them go cold at the thought – it has to be the duty of the expert to deal with the science and its meaning.  Of course, the reason that independent forensic scientists like me advocate for review of all science being presented in court is so that we can pick up problems like changes in findings that haven’t been notified to the court – not all scientists are transparent about what they do and there are also accidental errors and omissions – we are human after all.

Following on from that are the various requirements of professional organisations such as The Academy of Experts (their Model Form of Experts Report, for example), the Forensic Science Society of the UK (Vision and Values) and Australia/New Zealand (Code of Ethics) to name but a few.

In England and Wales, Part 33.2 (3) of the Criminal Procedure Rules indicates that the expert’s “…duty includes an obligation to inform all parties and the court if the expert’s opinion changes from that contained in a report served as evidence or given in a statement.” The work of the Forensic Science Regulator on Codes of Practice and Conduct and the European Network of Forensic Science Institutes involves a hefty degree of focus on the expert’s obligation to the court and advising of how scientific findings may have changed during the course of a case.

Any expert who doesn’t follow these guidelines shouldn’t be in the job.  Keeping evidence from the court is definitely not the way to go.