In Canada, the rule is established in R. v. Handy, 164 CCC (3d) 481, 2 SCR 908 (2002): Evidence of prior bad acts by the accused will be admissible if the prosecution satisfies the judge on a balance of probabilities that, in the context of the particular case, the probative value of the evidence in relation to a specific issue outweighs its potential prejudice and thereby justifies its reception.
Although preceding these changes, Rosemary West's 1995 trial has also been cited as an example where similar fact evidence was crucial to the prosecution case.
In a case of a Devon family imprisoned in 1998, one of the defendants appealed his conviction for raping his sister at the age of 16, suggesting it was unlikely that she would not complain or seek help.
It was held that the evidence that his father had coerced him into sexual acts with his other sisters as a child was similar fact evidence and, in addition to the systematic long-term sexual activity and abuse within the family, sufficient to explain why he felt that he could get away with abusing her and knew she could not rely on her family for protection; his appeal failed.
This evidence may be admissible for another purpose, such as proving motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake, or lack of accident.