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In a criminal trial, it is often the case that the prosecution wishes to impugn the character of the defendant by, for example, drawing the jury's attention to his or her previous criminal convictions (see evidence of bad character). There have been a number of striking cases in which the defendant was acquitted, when he or she would almost certainly have been convicted if the jury had know on his criminal past. However, it has until recently been a founding principle of English criminal law that a defendant's criminal or disreputable past may not be put in front of a jury. It was felt that to do this would undermine the general presumption of innocence which is the birthright of every Englishman blah blah blah...

The position at common law was that the prosecution could adduce evidence of the defendant's bad character only if the defendant put his own good character in issue (see putting character in issue), or under the rules on similar fact evidence. This evidence, if it was admissible at all, would only be admissible as evidence in chief, since at common law the defendant was not allowed to testify at all. After the coming into force of the criminal evidence act (1898), the defendant was able to testify and be cross-examined, and there were circumstances in which he could be cross-examined about his previous misconduct. However, this Act did not alter in any way the situation regarding evidence in chief -- only cross-examination.

Under the Criminal Justice Act (2003), the situation is rather different. Evidence in chief of the defendant's bad character can be adduced in the following circumstances:

1. when the parties are in agreement (s.101(1)(a)
2. when it is adduced by the defendant in his own testimony (most likely by accident) (s.101(1)(b))
3. when it is 'important explanatory evidence' (s.101(1)(c)), that is, important for an understanding of the case as a whole
4. when it goes to show the defendent's disposition to commit offences of the same description or 'category' as the present charge (s.101(1)(d), 103(1)(a))
5. when it goes to show that the defendant is untruthfull (s.101(1)(d), 101(1)(b))
6. when the defendant has given evidence that would undermine the defence of a co-defendant (s.101(1)(e))
7. it is necessary to correct a false impression given by the defendant (s.101(1)(f))
8. when the defendant has made an attack on another person's character (s.101(1)(g))

The provision in s.103(1)(a) -- evidence of a disposition to commit offences of the same description or category -- are similar to the common-law provision that 'similar fact' evidence can be admitted. s.103(1)(a) -- evidence necessary to correct a false impression -- encompasses the common-law provision that the defendant's bad character can be adduced if he puts his good character in issue, among other things. But note how many additional criteria there are under which evidence in chief of bad character may be admissible.

Note also that evidence of disposition, as a matter of disposition, includes evidence of past convictions for offenses of the same description or 'category'. It is left to the Home Secretary to determine what categories of offense there shall be.

See also evidence of disposition, Cross Examination As To Bad Character.