The headline from yesterday's Times says it all,
The story tells how Richard Dawkins is asking for a change to the libel laws because a number of reputable science writers are being sued for criticising what are thought to be pseudo-scientific alternative therapies (eg Simon Singh is being sued by the British Chiropractic Association).
There may be a lot to criticise with regard to libel laws but the criticism of the law should be aimed at the law surrounding how evidence is treated by the courts.
Lets quickly recap:-
In order for a trial to be lawful, it has to be fair: see Lord Diplock in Sang. One aspect of ensuring fairness in a trial is to ensure that evidence which is more prejudicial than probative is excluded from the trial. Another aspect of ensuring fairness is to exclude evidence based upon opinion: that is, except for evidence based upon expert opinion. However, an area of evidential law where evidence may be more prejudicial than probative may occur when scientific expert witnesses submit evidence in a trial. This is because a jury tends to believe an expert witness without question: would they be fulfilling their role if they didn't?
An example of evidence that was highly prejudicial but because it went beyond the witness's area of expertise, and so had no probative value was delivered by Professor Meadows in Clarke, 2003. The defendant was accused of murdering her two children who had died from cot-death. During the defendant's trial the expert wrongly gave the odds of two cot deaths occurring in the same household as one in 73 million. The defendant was convicted, subsequently freed on appeal but ended up meeting an early death (see Sally Clarke).
If expert opinion is allowed how do we know what is an expert opinion? Relating the question back to Dawkin's criticism; how do we know what is scientific expert opinion? Even though the courts allow this evidence; they aren't sure how to define it.
I appreciate that this beggars believe but consider what Weir J said in Hoey,
"The House of Commons Science and Technology Committee published on 25 July 2005 the Government's response to the Committee's Report "Forensic Science on Trial" which had been published on 29 March 2005. At paragraph 55 the Committee's comments on validation are repeated together with the Government's response. Both merit reproduction here:
"55. The absence of an agreed protocol for the validation of scientific techniques prior to their being admitted in court is entirely unsatisfactory. Judges are not well placed to determine scientific validity without input from scientists. We recommend that one of the first tasks of the Forensic Science Advisory Council be to develop a "gate-keeping" test for expert evidence. This should be done in partnership with judges, scientists and other key players in the criminal justice system, and should build on the US Daubert test.""
Hoey was the Omagh bomber case: a very distressing and emotive case that had to consider the scientific method of low copy number DNA. Mr Justice Weir very properly (and bravely) rejected the evidence gained from this technique but under very difficult circumstances - see his quote, above.
Weir J pleaded to have a Daubert - like system in-place, so what is Daubert?
It was a court case from the US that clarified how scientific expert opinion was to be classified and hence it gave criteria as to its admissibility. A woman fell pregnant, she took some morning sickness tablets; her child was born with a deformity (the baby had only one thumb and finger on one of its hands). Was this the fault of the drug company?
During the court case two scientific expert witnesses came to contradictory opinions which were tendered to the court: but which of the two opinions was admissible? The court case gave a number of criteria that allowed the judge to decide which of the opinions were scientific:-
"Faced with a proffer of expert scientific testimony ..., the trial judge, ..., must make a preliminary assessment of whether the testimony's underlying reasoning or methodology is scientifically valid and properly can be applied to the facts at issue. Many considerations will bear on the inquiry, including whether the theory or technique in question can be (and has been) tested, whether it has been subjected to peer review and publication, its known or potential error rate, and the existence and maintenance of standards controlling its operation, and whether it has attracted widespread acceptance within a relevant scientific community. The inquiry is a flexible one, and its focus must be solely on principles and methodology, not on the conclusions that they generate."
The case also gives as a criterion Popper's idea of falsifiability. But note that this only provides a persuasive precedent in our jurisdication.
In summary, the libel laws may be at fault but so are the admissibility of evidence laws and in the case of the admissibility (or otherwise) of scientific opinion evidence, in the presence of Daubert, glaringly.