Expanding on tsuwm's discussion a bit ...

In law, a moot point is one which presents only abstract questions of law which do not rest on existing rights or facts. Generally, an issue is moot when it is impossible for the court to fashion a remedy to the controversy. Normally, a court will decline to address a moot issue, but will address it if it presents a question of public significance which is likely to recur and yet evade judicial review.

It being the nature of people, litigation can tail off into a controvery whether the court should be deciding the underlying issue. It is possible for an intervening circumstance to then render the mootness issue moot.

But the word is fun to say. Moot moot moot moot moot ...