District Judge Julie Exton on the admissibility of similar fact evidence in civil cases
The concept of similar fact evidence is one that is well-known to criminal practitioners, although one that is not always easy to comprehend.
It admits evidence that does not directly implicate the accused in the offence charged but suggests, either directly or indirectly, that he has committed one or more other offences.
In DPP v P  AC 447, Lord Mackay concluded that the prerequisite is that the probative force in support of the allegation being tried is sufficiently great to make it just to admit the evidence, notwithstanding that it is prejudicial to the defendant in tending to show that he was guilty of another crime.
However, it was not necessary to show that there was some 'striking similarity' between the similar fact evidence and the evidence relating to the charge being tried.
The degree of similarity required will vary, according to the issues in the case and the nature of the other evidence.
But what application does this have in the civil arena? It is not something new.
And, like so much else, the modern expositions of the test to be applied in civil cases begin with a passage in the judgment of Master of the Rolls Lord Denning in Mood Music Publishing Co v de Wolfe Ltd  Ch 119 127: 'The criminal courts have been very careful not to admit such evidence unless its probative value is so strong that it should be received in the interests of justice - and its admission will not operate unfairly to the accused.
In civil cases, the courts have followed a similar line but have not been so chary of admitting it.
In civil cases, the courts will admit evidence of similar facts if it is logically probative, that is, if it is logically relevant in determining the matter which is in issue, provided that it is not oppressive or unfair to the other side, and also that the other side has fair notice of it and is able to deal with it.'
The problem most often crops up in civil actions against the police, for example for malicious prosecution.
So, in Thorpe v Chief Constable of Greater Manchester Police  1 WLR 665, the Court of Appeal did not consider that evidence that one or both of the police officers in that case had used excessive violence, effecting an arrest of some other person in some other circumstances, could be probative of the fact that they had used excessive violence against the plaintiff on the occasion complained of.
On the other hand, in Steel v Commissioner of the Metropolitan Police (CA, 10 February 1993), the court was influenced by the consideration that the police officer's conduct in the two comparator cases was 'so contrary to the expected standard of behaviour of an investigating officer' that it was capable of rendering it more probable that, in that case, the claimant's alleged confession was not made and that the officer had no sufficient belief in the grounds for the plaintiffs' prosecution, and an improper motive for instituting it.
And it is another civil action against the police that has provided the most recent guidance on the admissibility of similar fact evidence in civil cases: O'Brien v Chief Constable of South Wales Police  EWCA Civ 1085.
In 2000, after he had served 11 years of a life sentence, Michael O'Brien's conviction for murder was quashed.
In a civil claim, he alleged police malpractice and sought to adduce similar fact evidence from two other cases involving earlier investigations by the same police force (indeed, involving the same investigating officer).
The case confirms a two-stage test.
First, the question to be posed is whether the similar fact evidence is admissible.
To be admissible, it must be logically probative of an issue in the case and evidence, which is not sufficiently similar to the evidence in the case before the court must be excluded (as happened in Thorpe).
At this stage, the inquiry must be fact sensitive.
Second, once it is decided that the evidence is admissible, the court must then ask itself whether it ought, in the exercise of its discretion, to refuse to allow it to be admitted.
In deciding how to exercise its discretion, the court must have in mind the overriding objective of enabling the court to deal with cases justly (as opposed to Lord Denning's 'oppressive or unfair') and the various factors listed in the Civil Procedure Rules 1998 rule 1.1(2).
In principle, the Court of Appeal said, the stronger the probative force of the similar fact evidence, the more willing the court should be not to exclude it, all other things being equal.
However, a tendency to lengthen the proceedings and add to their cost and complexity might weigh against its admissibility unless there are strong countervailing arguments.
Any added complexity would be a particularly important consideration if there were to be a jury trial (as there often is, of course, in certain actions against the police)
This is all very well.
O'Brien was described by the Court of Appeal as having 'exceptional features' - and the judge at first instance was of the view that not only the importance and the seriousness of the case to Mr O'Brien, but also what he called the wider public interest, strongly favoured admission.
But what of more run-of-the-mill civil cases?
Take this example.
Mr Jones is a plumber.
He installs a new boiler for Mr and Mrs Smith but it is not up to the job.
He alleges they have fitted additional radiators.
The Smiths do not dispute this but say they told him that was their intention.
He denies this and it his word against theirs.
By chance, they learn from Mr Brown and from Ms White that Mr Jones has also fitted boilers for them which have not been adequate.
Does that evidence go in?
The test is still whether the proposed similar fact evidence is relevant in the sense that it is logically probative of an issue in the case.
If the evidence is logically probative of a person's normal conduct and the manner in which that person behaves (in this example, by going round fitting small boilers) is relevant to an issue in the case, then O'Brien (at paragraph 59) says that is enough.
The similar facts do not have to be elevated to a 'system of conduct' before they are admissible.
District Judge Julie Exton sits at Weston-super-Mare County Court