A motion to dismiss is a formal request (usually in a written motion) asking the court to dismiss a lawsuit or case for one of the reasons described in the relevant state or federal rule of civil procedure.

A motion to dismiss is usually filed in the early stages of the litigation and may be required before the party files any other pleading. Some of the common bases on which a case may be dismissed by the court include: (1) statute of limitations expired; (2) lack of subject-matter jurisdiction; (3) lack of personal jurisdiction; (4) improper venue; (5) insufficient process; (6) insufficient service of process; (7) failure to state a claim upon which relief can be granted; and (8) failure to join a party.

In Arizona, a motion to dismiss is governed by the Arizona Rules of Civil Procedure. Attorneys may file a motion to dismiss on behalf of their clients for various reasons, such as those listed in the description. These reasons include the expiration of the statute of limitations, lack of subject-matter or personal jurisdiction, improper venue, insufficient process or service of process, failure to state a claim upon which relief can be granted, and failure to join a necessary party. The motion to dismiss is typically filed after the complaint but before any other substantive pleadings. It challenges the legal sufficiency of the claims, and if granted, can result in the dismissal of the case either with prejudice (meaning the case is permanently dismissed) or without prejudice (allowing the plaintiff to potentially file the case again). The specific rules and procedures for filing such a motion are detailed in the Arizona Rules of Civil Procedure, and the outcome can significantly affect the course of litigation.