51   Lawful excuse

(1)  A person accused of an offence under section 50 in respect of the publication of matter defamatory of another person has lawful excuse for the publication where, but only where, if that other person brought proceedings against the accused for damages for defamation in respect of the publication of that matter, the accused would be entitled to succeed in those proceedings, having regard only to the events happening before and at the time of publication.

(2)  Where an information or other statement of a charge of an offence under section 50 alleges that the accused published the matter in question without lawful excuse, it is not necessary to negative, in the information or other statement, any thing which would amount to lawful excuse under subsection (1).

(3)  At the trial of a person accused of an offence under section 50, it is not necessary for the prosecution to negative any thing which would amount to lawful excuse under subsection (1) unless an issue respecting that thing is raised by evidence at the trial.