Bad influence

The past decades of well-publicised miscarriages of justice have afforded the Law Commission justification in the draft Criminal Evidence (Experts) Bill 2011 to take judicial, and even state, control of expert evidence in a criminal trial.

The bill provides a 'weak presumption' of expert reliability, but this can be rebutted by any party or trial judge, requiring it to pass a prescribed reliability test.

This test requires the party relying on expert evidence to prove, to no particular standard, that the hypothesis (science) it is based on is 'sound', and the 'strength' of the opinion justified.

This would require a trial judge to be an ad hoc scientific regulator, able to understand all the hypotheses, and most recent research, relating to the myriad of criminal actions before him '“ a herculean if not impossible task. Any judge's decision will inevitably usurp such hypotheses '“ or at least validate them '“ and produce precedent, a concept which is both incompatible and dangerous to the ever-changing world of scientific opinion.

If the hypothesis is found per se to be 'sound', the judge must then decide if the expert's opinion is justified, his data not flawed, his methods appropriate, and his inferences properly drawn. This requires a judge to assume the investigator's role and validate the scientific methodology and forensics that formed the basis of the opinion. Finally, he assumes the expert's role to decide if his inferences are justified by the facts, including inferences on the ultimate issues of the trial, removing a defendant's Magna Carta right to be tried on such issues by his peers.

The parties' lawyers would also be expected to have similar expertise if they are to represent their clients effectively in any Newton hearing held to decide this issue before the jury is sworn.

Eroding democracy

The cost, delay and workability of this statutory procedure can only be imagined, but is certainly not allowed for in today's criminal legal aid allowance or court lists. The bill will not only make justice more costly, but less accessible '“ particularly to defendants.

Similar American 'gate keeping' practices have already resulted in defence lawyers rarely, if ever, even applying for expert evidence to be excluded.

Faced with such an onerous task, and at risk of being appealed on a point of law, it is likely that a trial judge would feel the need to avail himself of the bill's option to defer his decision to a court expert, appointed by a panel established by the Lord Chancellor, whose decision on the present wording of the bill appears unappealable. Thus the commission proposes the executive be granted totalitarian control over the judiciary, in breach of the legal cornerstones of democracy '“ the separation of powers and the rule of law '“ and seriously eroding the adversarial system.

So, is such an unworkable, costly and constitutionally invasive change in the law justified or even necessary?

If examined, it can be seen that the recent miscarriages largely result from the prosecution's determination to obtain a conviction, at the cost of affording the defendant a fair trial. The prosecution hires experts who will achieve this, and who know they will not be rehired if they do not.

Failure to use the law

Judges and defence lawyers are also guilty of failing to ensure a fair trial by their inability to exclude patently inadmissible evidence. Professor Meadow's statistical evidence was inadmissible, as an opinion outside his expertise. His over 'spinning' of the statistics gave the court a second chance to exclude this evidence, as its likely effect on a jury would far outweigh its probative value. A very basic, adaptable exclusionary tool now codified in section 78(1) of the Police and Criminal Evidence Act 1984.

The court also allowed the prosecution pathologist to base his opinion on erroneously prepared blood slides, and withhold vital post-mortem tests. This travesty of justice was not caused by a failure of our existing common laws, but by the failure to use them to ensure Sally Clark received a fair trial.

Angela Canning was set free after expert evidence suggesting that her babies' cot deaths could have been caused by her familial genes was made available to the Court of Appeal. This evidence could and should have been found when investigating the offence. Interestingly, the proposed Act would not have prevented this miscarriage, as it specifically prohibits a trial judge from calling for any additional expert evidence other than the court-appointed expert.

Harris and Dallagher are examples of the prosecution being allowed to rely on, and the jury hear, weak, cumulated hypotheses (shaken baby syndrome and earprinting) which had little probative value, but proved highly prejudicial in a jury's eyes and should have been excluded.

The scandals of the bogus experts are merely further examples of the court not doing their homework properly.

This proposed bill would be a costly, unnecessary, and unjustified sledgehammer that will not crack this judicial nut and could instead bring judges under government control.