Military Law: a distinct legal system to which members of armed forces are subject. Military law deals with issues such as; procedures for military discipline, what is or what is not a lawful command, and obligations for service personnel. Military law can also be imposed on the civilian population instead of normal civil laws. In this instance it may be called martial law, and is often declared in times of emergency, war, or civil unrest. Most countries have restrictions on when martial law can be declared, and how long it can remain.