Principle of immutability of judgment; exceptions

Based on the principle of immutability of judgment, a decision must become final and executory at some point in time; all litigations must necessarily come to an end.
x x x A definitive final judgment, however erroneous, is no longer subject to change or revision.

A decision that has acquired finality becomes immutable and unalterable. This quality of immutability precludes the modification of a final judgment, even if the modification is meant to correct erroneous conclusions of fact and law. And this postulate holds true whether the modification is made by the court that rendered it or by the highest court in the land. The orderly administration of justice requires that, at the risk of occasional errors, the judgments/resolutions of a court must reach a point of finality set by the law. The noble purpose is to write finis to dispute once and for all. This is a fundamental principle in our justice system, without which there would be no end to litigations. Utmost respect and adherence to this principle must always be maintained by those who exercise the power of adjudication. Any act, which violates such principle, must immediately be struck down. Indeed, the principle of conclusiveness of prior adjudications is not confined in its operation to the judgments of what are ordinarily known as courts, but extends to all bodies upon which judicial powers had been conferred. x x x (Gonzales v. Solid Cement Corporation, G.R. No. 198423, October 23, 2012)
Subject to certain recognized exceptions such as (1) the correction of clerical errors; (2) the so-called nunc pro tunc entries which cause no prejudice to any party; (3) void judgments; and (4) whenever circumstances transpire after the finality of the decision rendering its execution unjust and inequitable, the principle of immutability leaves the judgment undisturbed as nothing further can be done except to execute it (Airline Pilots Association of the Philippines v. Philippine Airlines, Inc., 665 Phil. [2011]).