Removing Unreliable “Expert” Evidence from the Courtroom

The UK Law Commission has issued a report calling for greater scrutiny of expert evidence allowed in court, after a series of convictions were overturned (“declared unsafe” in UK legal language) because of shoddy or outright bogus evidence that was later debunked. This follows a rash of similar cases in the United States involving people convicted decades ago of serious crimes by using what was then considered reliable forensic techniques. In some cases, the forensic techniques were faulty. In others, the techniques were themselves sound, but improperly used by poorly trained, careless, or outright incompetent “experts”. Years or decades later, many of these people have been exonerated by scientific techniques (such as DNA typing) that were not available when they were convicted.

These errors have resulted in innocent people spending years, and in some cases decades, in prison.

Both we Americans and our British cousins tend to trust our scientists and our courts when it comes to establishing the facts. I don’t think that the trust in the scientific method or the basic judicial framework that we use is misplaced. However, non-scientists and non-lawyers often forget two things. First, no theory is perfect; all theories should be tested and refined regularly. Second, much of the outcome of a scientific experiment or a legal case is dependent, not upon good scientific or legal theory, but the implementation of that theory.

The scientific method accounts for these inconvenient facts: science consists almost entirely of an ongoing process of theory, experiment, and observation of the results. Scientists understand that results that disprove a theory are at least as important to science as those that prove a theory. The legal system, until recently, did not have a similar robust process for examining results that disprove the “theory” that the current legal process is the best way to determine the guilt or innocence of those tried in court.

This is now changing. Over a decade ago in the United States, a group of attorneys started the Innocence Project to examine cases of people wrongly convicted of felonies. This has resulted in a number of exonerations, some of them of people who had been sentenced to die for crimes that they did not commit. Now, in the United Kingdom, the Law Commission is also looking at wrongful convictions, and considering the causes.

I say — about d*mn time.

H/T to Daniel Cressey, who blogged about this in The Great Beyond, a blog in the science journal Nature.

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