Doctrine of Chances

The doctrine of chances is an evidentiary principle allowing prosecutors to introduce evidence of past similar incidents involving a defendant to show that it is highly improbable the defendant was repeatedly and innocently involved in comparable suspicious circumstances. It operates as an exception to the general rule, found in instruments such as Federal Rule of Evidence 404, that bars evidence of prior wrongful acts offered merely to show the character of a person or predict behavior. The doctrine traces to the 1915 English case Rex v. Smith, the so-called brides in the bath case, in which a man charged with drowning his wife in a bathtub was undone by evidence that two of his previous wives had died the same way; the pattern was judged too similar to be coincidence, letting the earlier deaths into evidence despite the usual bar on character evidence.