Military justice is the body of laws and procedures governing members of the armed forces. Many states have separate and distinct bodies of law that govern the conduct of members of their armed forces. Some states use special judicial and other arrangements to enforce those laws, while others use civilian judicial systems. Legal issues unique to military justice include the preservation of good order and discipline, the legality of orders, and appropriate conduct for members of the military. Some states enable their military justice systems to deal with civil offenses committed by their armed forces in some circumstances.

Military justice is distinct from the imposition of military authority on a civilian population as a substitute for civil authority. This condition is generally termed martial law, and is often declared in times of emergency, war, or civil unrest. Most countries restrict when and in what manner martial law may be declared and enforced.

All Commands of the Canadian Forces (CF) (that is, Royal Canadian Navy, Canadian Army, Royal Canadian Air Force, Canadian Operational Support Command, Canadian Expeditionary Force Command, Canadian Special Operations Forces Command, and Canada Command) are primarily governed by the National Defence Act (NDA). Section 12 of the NDA authorizes the governor in council's creation of the Queen's Regulations and Orders (QR&Os). The QR&Os are subordinate legislation having the force of law. Since the principle of delegatus non potest delegare has not achieved rigid standing in Canada, the QR&Os authorize other military officials to generate orders having similar, but not equal, status. These instruments can be found in the Canadian Forces Administrative Orders and Defence Administrative Orders and Directives; they are used as direction for authorities within the CF to administer the day-to-day considerations of the Forces.