(1)If on a defendant’s trial before a judge and jury for an offence—
(a)evidence of his bad character has been admitted under any of paragraphs (c) to (g) of section 101(1), and
(b)the court is satisfied at any time after the close of the case for the prosecution that—
(i)the evidence is contaminated, and
(ii)the contamination is such that, considering the importance of the evidence to the case against the defendant, his conviction of the offence would be unsafe,
the court must either direct the jury to acquit the defendant of the offence or, if it considers that there ought to be a retrial, discharge the jury.
(2)Where—
(a)a jury is directed under subsection (1) to acquit a defendant of an offence, and
(b)the circumstances are such that, apart from this subsection, the defendant could if acquitted of that offence be found guilty of another offence,
the defendant may not be found guilty of that other offence if the court is satisfied as mentioned in subsection (1)(b) in respect of it.
(3)If—
(a)a jury is required to determine under section 4A(2) of the Criminal Procedure (Insanity) Act 1964 (c. 84) whether a person charged on an indictment with an offence did the act or made the omission charged,
(b)evidence of the person’s bad character has been admitted under any of paragraphs (c) to (g) of section 101(1), and
(c)the court is satisfied at any time after the close of the case for the prosecution that—
(i)the evidence is contaminated, and
(ii)the contamination is such that, considering the importance of the evidence to the case against the person, a finding that he did the act or made the omission would be unsafe,
the court must either direct the jury to acquit the defendant of the offence or, if it considers that there ought to be a rehearing, discharge the jury.
(4)This section does not prejudice any other power a court may have to direct a jury to acquit a person of an offence or to discharge a jury.
(5)For the purposes of this section a person’s evidence is contaminated where—
(a)as a result of an agreement or understanding between the person and one or more others, or
(b)as a result of the person being aware of anything alleged by one or more others whose evidence may be, or has been, given in the proceedings,
the evidence is false or misleading in any respect, or is different from what it would otherwise have been.