In law, an issue or case being moot means that it has lost its practical significance because the underlying controversy has been resolved, one way or another. It is not only a matter of practicality as courts only have constitutional authority to resolve actual disputes. When no dispute exists and it would be futile to render any sort of judgment, a court may dismiss the case as moot.
Mootness can arise due to various reasons, such as:
- Voluntary cessation: The party being sued voluntarily stops the challenged activity or changes their behavior, making the case irrelevant. However, it must be noted that the Supreme Court has ruled that voluntary cessation of an unlawful practice will not usually moot its opponent’s challenge to that practice (See ArtIII.S2.C1.8.6 Voluntary Cessation Doctrine).
- Change in law: The legal issue in question has been resolved or rendered irrelevant by subsequent legislative or judicial action.
- Passage of time: The case has become outdated or irrelevant due to the passage of time, and the relief sought is no longer available or meaningful.
For a Supreme Court decision that focuses on mootness, see Arizonans for Official English v. Arizona, 520 U.S. 43 (1997).
[Last updated in June of 2023 by the Wex Definitions Team]