Similar-fact evidence

O’Brien v Chief Constable of South Wales Police HL TLR 29 April

The claimant’s conviction for murder was quashed after he had served 11 years of a life sentence. He claimed damages against the Chief Constable on the grounds that two police officers had acted oppressively and dishonestly in investigating the crime and he sought to adduce evidence of the same or similar conduct by the same officers in two other criminal cases. In civil proceedings, the test of admissibility of similar-fact evidence is that of relevance: the evidence must be potentially probative of an issue in the case. The judge with management of the litigation would then assess whether it should be admitted by reference to the need for proportionality and expedition in achieving a correct result through a trial process that was fair to all parties. In criminal proceedings the admissibility of similar-fact evidence required an enhanced relevance or substantial probative value because, if the evidence was not cogent, the prejudice that it would cause to the defendant might render the proceedings unfair. The test of admissibility built in protection for the defendant in the interests of justice. It led to the exclusion of evidence which was relevant on the ground that it was not sufficiently probative. This applied also to the evidence of bad character that the defendant wished to adduce against the police witnesses; the test of admissibility in criminal proceedings required an enhanced relevance in order to ensure that the ambit of the trial remained manageable. There was no warrant for the automatic application of either of those tests as a rule of law in a civil suit. To do so would build into civil procedure an inflexibility which was inappropriate and undesirable. The test was simply that of relevance. Such evidence was admissible if it was potentially probative of an issue in the action.