Similar Facts and Actus Reus

Some of the complexity of the English rules of evidence in criminal cases springs from a clash, probably dating back to the formative period of those rules, between two objects, laudable in themselves but antagonistic. One most fundamental principle, of which English lawyers are justly proud, stemming from a desire that a criminal trial should be conducted in a manner as fair to the accused as possible, was that evidence of his misdoings on other occasions should be prima facie inadmissible. On the other hand, courts of justice naturally desire that cogent and weighty evidence that the accused committed the crime with which he is charged should not be excluded from consideration by judge and jury, and consequently evidence, often called similar fact evidence, of other misconduct of the accused is sometimes receivable not because it shows his bad character but in spite of that fact.