22.—(1) The provisions of this Act have effect subject to any enactment or rule of law providing a defence, or providing lawful authority, justification or excuse for an act or omission.

(2) Notwithstanding subsection (1) any defence available under the common law in respect of the use of force within the meaning of section 18 or 19, or an act immediately preparatory to the use of force, for the purposes mentioned in section 18(1) or 19(1) is hereby abolished.