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Martial Law Explained

The law surrounding the concept is complicated and unsettled. Congress should pass legislation that better defines its scope.

Published: September 10, 2020

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. The limited Supreme Court preced­ent on martial law is old, vague, and incon­sist­ent. No federal stat­ute defines what the term actu­ally means. As a result, the exact scope and limits of martial law are danger­ously unclear. Congress and state legis­latures must enact new laws that better define them.

What is martial 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. But “martial law” has no estab­lished defin­i­tion, because across history, differ­ent people have used the term to describe a wide vari­ety of actions, prac­tices, or roles for the milit­ary. The law govern­ing it is complic­ated and unsettled — and, as a result, the concept has never been well under­stood.

Can the U.S. pres­id­ent declare martial law?

The Supreme Court has never clearly stated whether the federal govern­ment has the power to declare martial law, and if so, whether the pres­id­ent could unilat­er­ally declare it or whether it would require congres­sional author­iz­a­tion. However, the Supreme Court’s 1952 ruling in Young­stown Sheet & Tube Company v. Sawyer provides a frame­work for analyz­ing exer­cises of exec­ut­ive power — and would likely be used by a court to determ­ine whether a pres­id­ent’s martial law declar­a­tion has exceeded exec­ut­ive author­ity.

Accord­ing to Young­stown, when Congress has addressed an issue by passing a stat­ute, the pres­id­ent cannot act against Congress’s will — as expressed in the stat­ute — unless the Consti­tu­tion gives the pres­id­ent “conclus­ive and preclus­ive” power over that issue. When it comes to domestic deploy­ment of the milit­ary, Congress has expressed its will in two ways. First, it has enacted a wide vari­ety of laws that regu­late when and where the milit­ary may be used domest­ic­ally. These laws are so compre­hens­ive that Congress has “occu­pied the field,” mean­ing that if the pres­id­ent were to use the milit­ary domest­ic­ally in a way that Congress has not affirm­at­ively author­ized (such as by declar­ing martial law), it would effect­ively be against Congress’s will. Second, and more specific­ally, the Posse Comit­atus Act makes it illegal for federal milit­ary forces to parti­cip­ate in civil­ian law enforce­ment activ­it­ies — the exact sort of activ­it­ies that are asso­ci­ated with martial law — unless Congress has provided express author­iz­a­tion.

In short, Congress has placed clear and wide-ranging restric­tions on the pres­id­ent’s abil­ity to use the milit­ary domest­ic­ally. A pres­id­en­tial declar­a­tion of martial law would viol­ate these rules. The Consti­tu­tion does not grant the pres­id­ent “conclus­ive and preclus­ive” power over the issue of domestic milit­ary deploy­ment. On the contrary, it gives most of the relev­ant author­ity to Congress. There­fore, under Young­stown, the pres­id­ent would not have the consti­tu­tional author­ity to over­ride the restric­tions Congress has put in place, and a unilat­eral declar­a­tion of martial law would not survive a legal chal­lenge. 

What has Congress said about martial law?

There are no exist­ing federal stat­utes that author­ize the pres­id­ent to declare martial law. However, while Congress has passed a multi­tude of laws related to domestic milit­ary deploy­ment, these laws do not only create restric­tions. Congress has also given the pres­id­ent consid­er­able author­ity to use troops domest­ic­ally in ways short of martial law. The Insur­rec­tion Act, and poten­tially Title 32 as well, allow the pres­id­ent to deploy the milit­ary to assist civil­ian author­it­ies with law enforce­ment activ­it­ies virtu­ally whenever and wherever the pres­id­ent chooses. In some scen­arios, a deploy­ment of troops under these stat­utes might appear similar to a declar­a­tion of martial law. These ambi­gu­ities and the breadth of the pres­id­ent’s stat­utory author­ity point to the need for Congress to pass legis­la­tion that better defines the scope and limits of pres­id­en­tial powers — both for martial law and for other domestic uses of the milit­ary.

Does the Consti­tu­tion apply under martial law?

Yes. The federal govern­ment is bound at all times by the Consti­tu­tion. Even under martial law, the govern­ment cannot suspend or viol­ate consti­tu­tional rights. Addi­tion­ally, martial law declar­a­tions are subject to judi­cial review. For example, if the federal govern­ment places a state or territ­ory under martial law, indi­vidu­als detained by the milit­ary can ask a federal court to order their release by peti­tion­ing for the writ of habeas corpus. Subsequently, if a court considers the peti­tion, it can decide whether the declar­a­tion of martial law was consti­tu­tional in the first place.

Can states declare martial law?

The Supreme Court has held that indi­vidual states have the power to declare martial law — and such a declar­a­tion is valid simply if it is author­ized by the consti­tu­tion or laws of the state. States have declared martial law far more frequently than the federal govern­ment. However, even under martial law, state offi­cials are bound both by the U.S. Consti­tu­tion and by valid federal laws. Addi­tion­ally, indi­vidu­als can chal­lenge a state declar­a­tion of martial law by seek­ing injunct­ive relief in federal court — and if they are detained, they can peti­tion for the writ of habeas corpus.


Read the Bren­nan Center report Martial Law in the United States: Its Mean­ing, Its History, and Why the Pres­id­ent Can’t Declare It.