One of the excuses that appellate judges use to not decide a case is to hold that a case is moot .A matter is moot if further legal proceedings with regard to it can have no effect, or events have placed it beyond the reach of the law.
There are three major exceptions to this mootness rule. These are cases of "voluntary cessation" on the part of the defendant; questions that are "capable of repetition, yet evading review"; and questions involving class actions where the named party ceases to represent the class. Most commonly, a case is held to be moot when the status of a party is disputed and that party dies. The death of a defendant in a criminal case or the death of a person objecting to the terms of a divorce moots those cases.