Expert Evidence Must Be “Sufficiently Reliable” To Be Used In Criminal Proceedings

New criminal procedure rules came into effect in October 2014 which set out best practice for the use of expert evidence in criminal proceedings.

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Experts are used extensively in a large proportion of our cases and can often make the difference between a conviction and a successful outcome. Clients should beware of the new procedures, which plays a far greater emphasis on the courts than before in assessing the reliability of expert evidence and the credentials of those claiming to be experts.

The new practice direction CPD33A will come into play in any criminal case where expert evidence is called – for example DNA evidence, forensic accountancy evidence or computer analysis.

The new rules have been implemented at the recommendation of the Criminal Procedure Rules Committee.

The issue of expert evidence is one that has attracted some controversy in recent years. A Law Commission Report (Expert Evidence In Criminal Proceedings In England And Wales Report Number 325) on the use of expert evidence in criminal proceedings recommended that the courts adopt a more robust approach when deciding if expert evidence should be admitted.

However, the Government refused to act on the Law commission’s recommendations. So when the Criminal Procedure Rules Committee met to consider the issue, its proposed practice direction went further than the proposals advocated by the Law Commission and the new rules adopt the approach suggested a recent decision of the Court of Appeal in R v Duglosz, 1 Cr App R 425.

The new practice direction states that expert evidence can now only be admitted where the court is satisfied that there is a

“sufficiently reliable scientific basis for it”.

 Courts are now actively required to examine the reliability of expert evidence and should be

“astute to identify possible flaws in such opinion which detract from its reliability”

which include testing if the expert evidence is based on

“hypothesis which has not been subjected to sufficient scrutiny.”

All these developments point towards the need for clients to ensure that their lawyers are familiar with the latest developments in the rules governing the use of expert evidence in the criminal courts.