Azara Blog: Law Commission believes experts can be vetted by non-experts

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Date published: 2011/03/22

The BBC says:

Proposals to prevent people being wrongly convicted or acquitted on the basis of flawed expert evidence have been outlined by the Law Commission.

It says judges in England and Wales should be able to exclude evidence from experts such as scientists and doctors.

Evidence would fail a reliability test if an opinion was based on "flawed data", "unjustifiable assumptions" or techniques were not "properly applied".

In 1998, Mark Dallagher was found guilty of murder on the basis of expert evidence that he had left a unique ear print on a window pane at the crime scene.

After almost seven years in prison, Mr Dallagher was freed when DNA tests showed the ear-print was not his.

The Commission said the case demonstrates why courts should have a statutory power to prevent juries hearing unreliable expert evidence.

And the evidence of the paediatrician Professor Sir Roy Meadow was used in the Angela Cannings prosecution, which involved sudden infant death.

Mrs Cannings was found guilty of smothering her seven-week-old son in 1991 and her 18-week-old son eight years later.

These convictions were later overturned.

The judges who released her ruled that no-one should be prosecuted solely on the basis of medical opinion which was disputed between experts.

There are plenty of reasons for flawed convictions in English courts. For example, you can be convicted pretty much just on circumstantial evidence and on innuendo spread by the police and prosecuting authority and the media. And, as this article points out, you can be convicted based on flawed "expert" testimony. But the idea that judges will be able to figure out that some "experts" are not so expert beggars belief. In particular, how in the world are they going to know if an opinion is 'based on "flawed data", "unjustifiable assumptions" or techniques were not "properly applied"'? Would any judge currently seriously allow testimony to be taken at face value if it were deemed "flawed" or "unjustifiable"?

Needless to say, all "experts" have a world view and a paymaster, and that will influence their expressed opinion. But it is extremely unlikely that any non-expert will be able to pick holes in the evidence of an expert, at least during the initial trial. Most people (including "experts" and lawyers and judges) do not even understand the rudimentary principles of probability, and that is the main issue in many cases (e.g. the Cannings prosecution).

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