mootness

Mootness is a jurisdictional question because the Court 'is not empowered to decide moot questions or abstract propositions,' . . . our impotence 'to review moot cases derives from the requirement of Article III of the Constitution under which the exercise of judicial power depends upon the existence of a case or controversy.

Defined by the Supreme Court in - North Carolina v. Rice, 404 U.S. 244 (1971).