s 17 Defences: burden of proof
(1) This section applies where a person charged with an offence under this Act relies on a defence under any of sections 5(1) to (6), 6(1), 7B(5) and (7), 9(5), 10(3) and (4) and 15(3). (2) Where evidence is adduced which is sufficient to raise an issue with respect to that defence, the court or jury shall assume that the defence is satisfied unless the prosecution proves beyond reasonable doubt that it is not.