Duress by Threats

CPS legal guidance states the scope of the defence, and its exceptions, directly: 'Duress is a common law defence to all crimes except murder, attempted murder and treason involving the death of the sovereign', citing R v Gotts [1992] 2 AC 412 as authority. Where it is available, duress operates as a complete defence rather than merely reducing the offence or the sentence.

Whether the defence succeeds turns on an objective standard rather than the defendant's own perception of the threat. The guidance explains that 'The question of whether a threat or circumstances compelled a person to act as they did involve the application of an objective test: would the threat or circumstances have had that effect on a person of reasonable firmness?' A narrow exception allows a jury to take a defendant's mental health into account when assessing susceptibility to the threat, but only where a recognised medical condition is supported by expert evidence.