Mostly it refers to the lack of authority of a judge to rehear a case after it has rendered judgment; they are "void of office".
In Chandler v Alberta Association of Architects, Justice Sopinka wrote in relation to the principle of functus officio:
"The general rule (is) that a final decision of a court cannot be reopened....
"The rule applied only after the formal judgment had been drawn up, issued and entered, and was subject to two exceptions: where there had been a slip in drawing it up, and where there was an error in expressing the manifest intention of the court."
In the context of criminal law, Ruby wrote:
"The expression functus officio means having discharged a duty.
"When used in relation to a court, it may also mean whose duty or authority has come to an end.
"Once a court has passed a valid sentence after a lawful hearing, it is functus officio and cannot repoen the case."
Many losing litigants misunderstand the finality of a judicial decision and hope to re-engage the court by suggesting a missed point or new evidence. To promote finality of judicial decisions which would otherwise be subject to applications to reopen the case by all disappointed litigants, once a decision is issued, the judge loses his/her authority to further rule on it. He/she is without authority; no longer seized of the litigation; functus officio. This leaves the litigant with the sole recourse of an appeal.
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