Mootness asks whether a real, live dispute still exists by the time a court is ready to rule. Even if a case presented a genuine controversy when filed, intervening events can eliminate the actual stake — the parties settle, the challenged conduct stops and can't recur, or the requested relief becomes impossible or pointless to grant — and once that happens, courts generally lack authority to decide what has become a purely hypothetical or academic question.

The doctrine has recognized exceptions for situations that would otherwise evade review — disputes capable of repetition yet evading review (like short-duration events that always resolve before litigation can finish), voluntary cessation by a defendant who could simply resume the challenged conduct later, and certain class-action contexts where the named plaintiff's individual claim becomes moot but the class's claims survive.

Juricratic checks mootness as a live-controversy gate on a simulated matter's continued relevance — a claim that has gone moot stops generating meaningful outcome distributions in the model, since there is, by definition, no longer a real-world stake left for the simulation to be estimating.

Litigators watch for developments that could moot a claim — a policy change, a completed transaction, a settlement of a portion of the case — because a genuinely moot claim can be dismissed regardless of its underlying merits, ending litigation before any court reaches the substantive question. Counsel seeking to avoid mootness sometimes act quickly to preserve a live controversy (for instance, seeking expedited relief) precisely because delay itself can moot out the very issue they're trying to litigate.