11. Similar-fact evidence

Makin v Attorney-General for New South Wales is the starting point. John and Sarah Makin took in infants for payment. The bodies of babies were found buried in the gardens of houses where they had lived. At the trial for the murder of one child, the prosecution proved the other bodies and the other payments. Lord Herschell stated both halves of the rule. It is not competent for the prosecution to prove that the accused has been guilty of other criminal acts only in order to show that he is a person likely, from his criminal character, to have committed the offence charged. The other acts may be relevant if they bear upon the question whether the acts alleged were designed or accidental, or whether they rebut a defence which would otherwise be open to the accused.

Before DPP v Boardman, the cases were often taught in categories. Accident: R v George Joseph Smith, the brides in the bath, three wives found drowned shortly after a form of marriage, a will or an insurance, and the same pattern of death. Mistake, or an innocent medical explanation: R v Bond. Innocent association: R v Ball, a brother and sister charged with incest, and evidence that they had lived as husband and wife and had a child. Identity: R v Straffen, and R v Thompson, where powder puffs and indecent photographs of boys were admitted to support the identification of the man the boys had described.

Straffen shows why identity is the strongest category. Two girls had been killed in a peculiar way: strangulation, no sexual interference, no attempt to hide the body. Straffen was in Broadmoor. He escaped for a few hours. A third girl was found dead, nearby, in the same way. Evidence of the earlier killings was admitted on the third charge because the peculiarity pointed to the same person.

Boardman did not overrule Makin. It changed the emphasis. The accused was the headmaster of a boarding school. Boys said he had come into their dormitory at night and invited them to take the active part in acts of buggery. The House of Lords held that the evidence of one boy could be used on the count concerning another. The test is the probative force of the evidence. There must be a striking similarity, such that to explain the similarity as coincidence would be an affront to common sense. The old categories matter less than the degree of relevance.

Later cases warned against treating "striking similarity" as a spell. In R v Rance and Herron, Widgery LCJ said the phrase should not be over-weighted. In R v Scarrott the question was positive probative value, and a link between the evidence and the charge, not mere repetition of similar allegations.

DPP v P is the modern statement. A father was charged with the rape and incest of two daughters. The features were the use of discipline, payment for abortions, and the mother's acquiescence. The Court of Appeal called that the stock-in-trade of an incestuous father, found no striking similarity, and quashed the conviction. The House of Lords restored it. Lord Mackay of Clashfern said striking similarity is only one way of showing the required probative value. The question is whether the probative force of the evidence is strong enough to make it just to admit it, notwithstanding the prejudice. It was, on those facts. R v H followed P.

The prejudice is obvious. A jury told that a man has done the same thing before may convict because he is a bad man, not because this charge is proved. That is why propensity, standing alone, is excluded, and why the judge has to be satisfied of the positive probative value before the evidence goes in.