Truth (or justification) is a complete defence to an action for defamation.

The defendant (the alleged defamer) must prove that the defamatory imputation carried by the material published is substantially true. For example, a person who says that someone is a murderer must prove the fact of murder. Where defamatory matter carries several imputations, it is a defence if the reputation of the plaintiff is not harmed other than by the defamatory imputations which are proved to be true [Defamation Act 2005 (SA) s 24].

Where the defendant (the alleged defamer) proves that the matter carried 1 or more imputations that are substantially true (contextual imputations) and that any defamatory imputations of which the plaintiff complains that are not contextual imputations (i.e. because they are not proved to be true) do not further harm the reputation of the plaintiff because of the substantial truth of the contextual imputations, then the defence of contextual truth succeeds.

The contextual imputations on which the defendant may rely to establish the defence of contextual truth can include imputations of which the plaintiff has complained. In other words, in order to establish the defence, a defendant may plead back (as contextual imputations) any substantially true imputations originally pleaded by the plaintiff.

For example, if a publication carries imputations that a professional person has intentionally deceived a client and has also stolen another client’s money and only one of the imputations is proved to be true, that may be sufficient to defend the whole publication through the defence of contextual truth.