Martial law is the temporary replacement of civilian government by military rule and the suspension of civilian legal processes for military powers. It can be declared in times of war, rebellion, natural disaster, or civil disorder, when civilian authority has ceased to function, is completely absent, or has become ineffective. Here are some key points about martial law:

• The legal effects of a declaration of martial law differ in various jurisdictions, but they generally involve a suspension of normal civil rights and the extension to the civilian population of summary military justice or of military law.

• In the United States, martial law usually refers to a power that, in an emergency, allows the military to take the place of the civilian government and exercise jurisdiction over civilians in a particular area.

• Martial law has been declared more than 60 times in U.S. history, mostly by state and local officials. However, the concept has no established definition, and the exact scope and limits of martial law are dangerously unclear.

• The military commander of an area or country has unlimited authority to make and enforce laws under martial law. Martial law suspends all existing laws, as well as civil authority and the ordinary administration of justice.

• The power of martial law, once held to be nearly absolute, has limitations. For example, civilians may not be tried by military tribunals as long as civilian courts are functional.

• Martial law can be declared by the U.S. president, the governor of a state, or, in limited emergencies, by a local military commander. How and when it is declared is governed by a series of laws.

• Martial law has been declared in the U.S. and its territories 68 times, according to the Brennan Center for Justice. Natural disasters, riots, and even labor strikes have all resulted in the civilian government temporarily ceding its power to the military.