Chapter 2 contains “all the general principles of criminal responsibility that apply to any offence”: s2.1 Purpose. Accordingly it was necessary to provide a general defence which will excuse or justify conduct which is authorised by law. The law in question must be a law of the Commonwealth: Dictionary. Typical examples for an application of s10.5 are those provisions which confer investigatory powers on police and other officials, and permits for the import or manufacture of weapons, explosives or drugs…&c. The reference to conduct which is justified or excused “by or under a law” recognises that the authorisation may be indirect or implied, rather than explicit.267
As in other defences, the defendant bears the evidentiary burden: s13.3 Evidential burden of proof – defence. Once the defence is raised by evidence, the prosecution must prove beyond reasonable doubt that the conduct was not authorised.268
