There is no doubt that, prior to a final judgment being delivered and the record of it being 'drawn up, passed and entered', a superior court of record has full power to rehear the proceedings and vary the judgment pronounced. See Texas Co (Australasia) Ltd v Federal Commissioner of Taxation. ...
Ordinarily, once a court has pronounced judgment, ... and final orders are made, ... and perfected, the Court which made those orders is functus officio (R v Cripps; Ex parte Muldoon), and its power to reconsider the subject matter of the proceedings is at an end: Burrell v The Queen.
As so often happens in the law, there are, to this rule, exceptions.
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[The Applicant Defendants] seek that the order and judgment be set aside because of a fundamental defect that, they submit, so infects the judgment that it cannot stand; it is, they assert, a nullity.
Such an application is sometimes described as based on the entitlement to relief from an injustice; that is, the Applicant Defendants are entitled ex debito justitiae to have the judgment set aside. As was said in Craig v Kanssen:
Those cases appear to me to establish that a person who is affected by an order which can properly be described as a nullity is entitled ex debito justitiae to have it set aside. So far as procedure is concerned, it seems to me that the court in its inherent jurisdiction can set aside its own order, and that it is not necessary to appeal from it.
A judgment which has been procured by a failure to observe the rules of natural justice would be an example of where the judgment is a nullity: Hoskins v Van Den-Braak.
This is an inherent power in the Court and does not depend on any statutory power: Isaacs v Robertson.[59]