It is a defence for a person (P) charged with an offence under section 2(1)(a) or (c) to (g) to show that, at the time of the conduct constituting the offence, P neither knew nor suspected, nor had reason to suspect, that the object in question was a prohibited munition.

It is a defence for a person (P) charged with an offence under section 2(1)(e) to show that, having come to know or suspect while the object in question was in P's possession that it was a prohibited munition, P took all reasonable steps, as soon as reasonably practicable after P first had that knowledge or suspicion, to inform the Secretary of State, or a constable or member of a service police force, of P's knowledge or suspicion.

It is a defence for a person (P) charged with an offence under section 2(1)(e) to show that P did not have any knowledge or suspicion that the object in question was a prohibited munition, nor any reason for such a suspicion, until P became aware of the Secretary of State's exercise in the case of that object of a power conferred on the Secretary of State by this Act.

It is a defence for a person (P) charged with an offence under section 2(2) to show that, at the time of the assistance, encouragement or inducement, P neither knew nor suspected, nor had reason to suspect, that the conduct assisted, encouraged or induced related, or might relate, to a prohibited munition.