Although the law is subject to sudden change in this area, as of 2007, absolute privilege protects persons from tort claims alleging defamation where the alleged defamatory statements were made by members of legislative assemblies while on the floor of the assembly or communications made in the context of judicial proceedings, as part of a trial.
It may also extend itself to "official communication relating to state affairs, including commercial matters, made by one officer of state to another in the course of his official duty" (Halsbury's Laws of England, 4th ed., vol. 28).
In term of judicial proceedings, this was said in Teskey v Toronto Transit Commission 2003 OJ 5314 (Ontario, Quicklaw):
"Historically, the courts have recognized an absolute privilege against action for those participating in a trial.
"Absolute privilege exists to protect freedom of speech in court proceedings. If absolute privilege applies, a person making a deliberate false statement is protected from civil suit. The recognized core of absolute privilege applies to everything that is said in a judicial proceeding by witnesses, prosecutors and by judges. Core absolute privilege is recognized and enforced in Canada.
"Absolute privilege protects witnesses doing their public duty from civil action to ensure the cooperation of the public in the criminal justice system.
In this area of the law in Canada, one author has clearly made a mark with his book The Law of Defamation in Canada. His definition of absolute privilege is often quoted, such as this extract from Dechant v. Stevens 2001 ABCA 39:
"Absolute privilege has been conceded on obvious grounds of public policy to insure freedom of speech where it is essential that freedom of speech should exist.
"It is essential to the ends of justice that all persons participating in judicial proceedings should enjoy freedom of speech in the discharge of their public duties or in pursuing their rights, without fear of consequences.
"The purpose of the law is, not to protect malice and malevolence, but to guard persons acting honestly in the discharge of a public function, or in the defense of their rights, from being harassed by actions imputing to them dishonesty and malice. Freedom from vexatious litigation for honest participants is so important that the law will not take the risk of subjecting them to such danger in order that a malicious participant may be mulcted in damages.
"The true doctrine of absolute immunity is that, in the public interest, it is not desirable to inquire whether utterances on certain occasions are malicious or not. It is not that there is privilege to be malicious, but that, so far as it is a privilege of the individual, the privilege is to be exempt from all inquiry as to malice; the reason being that it is desirable that persons who occupy certain positions, as judges, jurors, advocates, or litigants, should be perfectly free and independent, and that to secure their independence, their utterances should not be brought before civil tribunals for inquiry on the mere allegation that they are malicious.
"The rule exists, not because the malicious conduct of such persons ought not to be actionable, but because, if their conduct were actionable, actions would be brought against them in cases in which they had not spoken falsely and maliciously: it is not a desire to prevent actions from being brought in cases where they ought to be maintained, but the fear that if the rule were otherwise, numerous actions would be brought against persons who were acting honestly in the discharge of duty."