Mutiny is the crime of conspiring to disobey orders that the mutineer is legally obliged to obey, for example by crew members of a ship.

The Royal Navy's Articles of War have changed slightly over the centuries they have been in force, but the 1757 version is representative – except that the death penalty no longer exists – and defines mutiny thus:

Article 19: If any person in or belonging to the fleet shall make or endeavor to make any mutinous assembly upon any pretence whatsoever, every person offending herein, and being convicted thereof by the sentence of the court martial, shall suffer death: and if any person in or belonging to the fleet shall utter any words of sedition or mutiny, he shall suffer death, or such other punishment as a court martial shall deem him to deserve: and if any officer, mariner, or soldier on or belonging to the fleet, shall behave himself with contempt to his superior officer, being in the execution of his office, he shall be punished according to the nature of his offence by the judgment of a court martial.

Article 20: If any person in the fleet shall conceal any traitorous or mutinous practice or design, being convicted thereof by the sentence of a court martial, he shall suffer death, or any other punishment as a court martial shall think fit; and if any person, in or belonging to the fleet, shall conceal any traitorous or mutinous words spoken by any, to the prejudice of His Majesty or government, or any words, practice, or design, tending to the hindrance of the service, and shall not forthwith reveal the same to the commanding officer, or being present at any mutiny or sedition, shall not use his utmost endeavours to suppress the same, he shall be punished as a court martial shall think he deserves.

The United States's Uniform Code of Military Justice defines mutiny thus:

Article 94: Mutiny or Sedition. A member who, with intent to usurp or override lawful military authority, refuses in concert with any other person, to obey orders or otherwise do his or her duty or creates any violence or disturbance, is guilty of mutiny. A person who, with intent to cause the overthrow or destruction of lawful civil authority, creates, in concert with any other person, revolt, violence, or other disturbance against that authority, is guilty of sedition. Furthermore, a member who fails to do his or her utmost to prevent and suppress a mutiny or sedition being committed in his or her presence, or fails to take all reasonable means to inform his or her superior commissioned officer or commanding officer of a mutiny or sedition which he or she knows or has reason to believe is taking place, is guilty of a failure to suppress or report a mutiny or sedition. Violations of this article can be punished by death.

Famous mutinies

• Corkbush Field mutiny (1647) by soldiers New Model Army who supported the Levellers.
• Mutiny on HMS Bounty (1789)
• Spithead and Nore mutinies (1797)
• Indian Mutiny (1857)
• The Potemkin mutiny in Russia in 1905
• French Army Mutinies in 1917 (see World War I#The trenching begins)
• Part of the crew of Russian cruiser Aurora joined the 1917 February Revolution and at 21:45 7 November 1917, a blank shot from her forecastle gun signalled the start of the attack on the Winter Palace, which was to be the first episode of the communist Russian Revolution.
• The Wilhelmshaven mutiny started October 29 1918 (see Weimar Republic)
• The "Kinmel Park Camp" mutiny [1] March 1919
• The Invergordon Mutiny, 1931
• The Port Chicago mutiny, 1944
• The SS Columbia Eagle incident, March 1970