Posse Comitatus Act

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The Posse Comitatus Act (1878)prohibited use of the U.S. Army to aid civil officials in enforcing the law or suppressing civil disorder unless expressly ordered to do so by the president. Southern Democratic members of the House who resented widespread use of federal troops during Reconstruction introduced the law. Some northern congressmen supported the law due to the army's role in suppressing disorders during the 1877 railroad strike.

In the past, soldiers had occasionally served as posses to assist U.S. marshals or judges without reference to the president. During the 1850s, U.S. Attorney General Caleb Cushing ruled that U.S. marshals could call upon federal soldiers, Marines, and sailors to help enforce the Fugitive Slave Act in the North. Such troops performed similar duties when called on by territorial governors in Kansas and Utah. Regulars routinely acted as posses during Reconstruction in the South, particularly during election disorders. Troops suppressing the 1877 railroad riots took orders from state governors and even municipal officers.

Use of federal troops as a posse comitatus placed them outside the military chain of command and the commander in chief's direct authority. Too often the practice turned regulars into policemen serving the interests of locals directly involved in the disputes provoking disorder. Army officers welcomed the Posse Comitatus Act and the new regulations it engendered, for they felt more comfortable performing their duty safely within the chain of command. The provisions of the act have governed army regulations and civil disorder doctrine to the present.
[See also Civil‐Military Relations; Commander in Chief, President as.]

Bibliography

Robert W. Coakley , The Role of Federal Military Forces in Domestic Disorder, 1789–1878, 1988.
Jerry M. Cooper , Federal Military Intervention in Domestic Disorders, in Richard H. Kohn, ed., The United States Military Under the Constitution of the United States, 1789–1989, 1991.

Jerry Cooper

Posse Comitatus Act 1878, U.S. federal law that makes it a crime to use the military as a domestic police force in the United States under most circumstances. The law was designed to end the use of federal troops to supervise elections in the post–Civil War South. The posse comitatus (from which the term posse derives) is the power or force of the county, and refers to citizens above the age of 15, who may be summoned by a sheriff to enforce the law. The act specifically prohibited the use of the U.S. army as a posse comitatus; the prohibition was later extended by legislation to the air force and by government directive to the marine corps and navy. The restriction does not apply to the coast guard during peacetime or the national guard when it is under state authority. There are legal exceptions to the law, particularly in aspects of drug law enforcement, in emergency situations, and in cases of rebellion.

Posse Comitatus Act a law enacted in 1878 to prohibit the use of the U.S. army in civilian law enforcement, unless otherwise instructed by the president, thereby excluding the military from the civilian sphere. After President Ulysses S. Grant sent a posse comitatus to the polls in the election of 1876, it was presented by Southern Democratic members of the House who resented the use of federal troops during Reconstruction.