Michael O'Brien v Chief Constable of South Wales Police [2005] UKHL 26

1. Michael O'Brien v Chief Constable of South Wales Police
[2005] UKHL 26
The respondent’s conviction for murder was quashed after he had served 11 years of a life
sentence. Respondent 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.
The appellant chief constable appealed against a decision that similar fact evidence was
admissible in a claim brought by the respondent for misfeasance in public office and
malicious prosecution.
The Court of Appeal applied to the test of admissibility in civil proceedings the approach
adopted in criminal proceedings. The judge had to decide whether the evidence was
admissible and then whether as a matter of discretion he would permit the evidence to be
led. Evidence of the similar incidents alleged by respondent was admitted.
The chief constable contended that there was a rule of law which prevented the admission
of similar fact evidence unless it had an enhanced probative value.
The court dismissed the appeal. The court inter alia stated that it was incorrect that similar
fact evidence was only admissible in a civil suit if it was likely to be reasonably conclusive of
a primary issue in the proceedings or alternatively if it had enhanced relevance so as to have
substantial probative value.
The test of admissibility of similar facts against a defendant in criminal proceedings required
an enhanced relevance or probative value because, if the evidence was not cogent, the
prejudice that it would cause to the defendant might render the proceedings unfair. If a
defendant wished to adduce evidence of bad character against a police witness, the test of
admissibility required an enhanced relevance in order to ensure that the trial remained
manageable. There was no reason 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 appropriate test for similar fact evidence in a civil suit was relevance. Such evidence was
admissible if it was potentially probative of an issue in the action.
Nevertheless, policy considerations would still have a part to play in the conduct of civil
litigation and the court had the power to exclude evidence that would otherwise be
admissible and to limit cross-examination.

2. Furthermore, judges should be clever to see that the probative cogency of similar fact
evidence justified the risk of prejudice in the interests of a fair trial.
In the instant case the evidence was potentially probative and therefore admissible.
The House of Lords therefore affirmed the decision of the Court of Appeal and dismiss the
appeal.