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February 27, 2006

Sometime expert witness Theodore Dalrymple explains the problem with expert testimony: mavericks and the upholders of orthodoxy are treated as equals

Posted by Theodore Dalrymple

In the light of the High Court decision to reinstate Sir Roy Meadow to the Medical Register, sometime expert witness Theodore Dalrymple explains what he sees as the problem with expert testimony. The conflicting opinions of different experts are treated as equal - even when one expert represents the orthodoxy and the other is a maverick whose views are rejected by ninety-nine out of every hundred of his peers.

As a sometime expert witness, I was relieved by the decision of the High Court to order the reinstatement of Professor Sir Roy Meadow to the Medical Register. My faith in the disciplined common sense of judges was restored. It seemed to me that the General Medical Council's original decision to strike Sir Roy off the Register was at best a mistake, at worst a cowardly genuflection to a sectional private interest.

Sir Roy, as I am sure most people will remember, was held responsible by several women for their wrongful conviction for the murder of their babies. Their anger – and that of their relatives - was understandable. In his testimony, Sir Roy simply squared the statistical chance of a baby dying by cot death in order to estimate the chances of two babies in the same household dying of cot death: a calculation that would have been correct only if there were no factors, genetic, congenital or environmental, that conduced to cot death.

This not being the case, a very misleading impression of the likelihood of two (or more) such deaths occurring in the same household was given to the courts. But no one is convicted on the say-so of an expert witness alone. The whole point of the adversarial system of justice is that the evidence should be tested. The defence lawyers and the experts they instructed did not correct the statistical error, and therefore it could not have been quite as obvious, even to highly intelligent men, as sometimes alleged.

Moreover, the guilt of any particular person does not follow from the fact that someone has been done to death in the household in which he lives. Expert evidence can therefore never in itself convict anyone of anything.

Not even Sir Roy's worst enemies have suggested that he acted in bad faith: that he said something that he did not believe to be true at the time. But those who disagreed with his restoration to the Medical Register have claimed that Mr Justice Collins’ judgement, that mistakes by expert witnesses cannot be the grounds of professional disciplinary proceedings against them, leaves expert witnesses free of all constraint.

This is not so. Expert witnesses still have a duty to be truthful: not to enunciate the Truth, which is vouchsafed to no one, but to tell the truth as they see it. Like all other witnesses, they may not deliberately tell lies for any reason or knowingly twist their evidence to establish the guilt or innocence of the accused, even after Mr Justice Collins' ruling.

Nevertheless, there are undoubtedly problems with expert testimony under the adversary system. For example, the defence will often call an expert witness who, while undoubtedly an expert and a sincere man, is a maverick, who believes in a theory that is rejected by ninety-nine out of a hundred of his peers. The comparative weight of his opinion, however, is grossly exaggerated by his appearance in court when he appears in refutation of the more orthodox theory. The impression is given to the jury that experts disagree, and that the question at issue is a completely open one, the maverick's theory being equal in value to the orthodox expert's theory.

One obvious solution to the problem is to have court-appointed experts: but this has its dangers, too. The court-appointed expert becomes an oracle, especially with age and experience, and much as it is delightful to be an oracle, I should not myself care to be tried in a court where experts act as oracles. Mistakes being inevitable under all conceivable systems of justice, the adversary system is probably the best possible.

Of course, even the question of an expert's bona fides can be a difficult one to answer. I was once involved in a case in which a student was caught in possession of a quantity of drugs greater than that which would be accepted as being plausibly for his individual use: and the offence of possession with intent to supply carries much heavier penalties than mere possession.

He had, however, taken some of the drug himself, not very long before he was questioned by the police. The defence alleged that he was under the influence of the drug during police questioning, and that therefore the interview should not be admitted into evidence.

I was one of two doctors asked to give an opinion as to whether he was so under the influence of the drug that his answers to questions could be deemed unreliable. My opinion was that there was nothing in the interview record to suggest that he was other than perfectly normal at the time. He was not excitable, irritable or incoherent, and he certainly said nothing that was bizarre.

The other doctor was a well-known advocate of the complete legalisation of the consumption of all currently-illicit drugs. It wasn't just that he thought that prohibition gave rise to crime; he thought that self-indulgence in mind-altering substances was a positive good. As a faithful child of the 60s, he believed in the concept of expanded consciousness.

He did not go so far as to say that the interview demonstrated that the accused was under the influence at the time; rather, he said that it could not be ruled out that he was under the influence.

In this, he was strictly speaking correct. No one could have said that, had the accused not taken the drug, he would not have answered the questions he was asked any differently from the way he did answer them. It was beyond the powers of anybody in the world to assert such a thing.

But the doctor in question was asked a simple question that he refused to answer in a straightforward fashion: was there any evidence in the interview record to suggest that the accused was under the influence? Like an accused who answers all questions with,

No comment
he always replied,
It cannot be ruled out
- no matter how many times the question was asked.

He tailored his answer to his belief that the case should not have been brought in the first place, that it was the accused's inalienable right to supply drugs if he wanted to.

In the event, the accused changed his plea to guilty. I have little doubt that he would have been found guilty had he insisted on pleading not guilty. Was the other doctor in the case dishonest, and should he have been struck off the register if he was? After all, he had told no lies, unless evasiveness be a lie.

As usual, it is difficult to establish a rule to cover all cases. This is something that the would-be regulators of the world wish never to remember.

Theodore Dalrymple is a writer and recently retired as an inner city and prison doctor.

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