Limiting the Military’s Role in Law Enforcement

In May 1992, seven U.S. Marines joined two local police officers as they responded to a domestic violence call in the waning days of the Los Angeles riots. Deployed to the city alongside several thousand other federal troops after President George H. W. Bush invoked the Insurrection Act, these Marines now found themselves playing a role for which they had little training: that of civilian law enforcement officer.

At the scene, as the police officers prepared to enter the home, someone inside fired a shotgun through the door. One of the officers shouted to the Marines, “Cover me” — a request, in law enforcement parlance, that they raise their weapons and be ready to fire if necessary. But the Marines, in accordance with their own training, took it as a request for suppressing fire. They riddled the home with more than 200 bullets. Miraculously, no one was killed. footnote1_gmhwteiNnrEwfaKZnKwdZWZp9PTMGfaM27ugTDnRNbU_bExKVYjgxJJL1See Kyle Daly, “1992: Rioting in Los Angeles,” Leatherneck, October 2020, 30, 34, https://www.mca-marines.org/wp-content/uploads/1992-Riots-in-Los-Angeles.pdf. See also Paul J. Scheips, The Role of Federal Military Forces in Domestic Disorders, 1945–1992 (Washington, DC: Center of Military History, United States Army, 2012), 448, https://www.govinfo.gov/content/pkg/GOVPUB-D114-PURL-gpo82975/pdf/GOVPUB-D114-PURL-gpo82975.pdf.

In the United States, federal military participation in civilian law enforcement like this has been rare, particularly over the past half century. The idea of tanks rolling down the streets of American towns and soldiers dressed in camouflage apprehending Americans is anathema to modern sensibilities. Some Americans might even assume that these actions are prohibited by the U.S. Constitution. Indeed, the use of federal troops as a domestic police force is in tension with both constitutional principles and long-standing American traditions, which were informed by the British government’s heavy-handed use of the military to police the colonies in the years leading up to the American Revolution. Events like the Boston Massacre illustrated to the founding generation the dangers of domestic deployment of the military. But while the Constitution limits military involvement in civilian affairs in various ways, it does not entirely bar the federal armed forces from conducting law enforcement activities. A partial prohibition comes instead from a law passed by Congress in 1878: the Posse Comitatus Act.

The Posse Comitatus Act rests at the center of a web of laws, regulations, and policies that govern what the U.S. military can and cannot do domestically. It is a crucial safeguard for the preservation of both American democracy and constitutional liberties. At the same time, it is riddled with exceptions, loopholes, and ambiguities that leave it surprisingly weak. The most dangerous exception by far is the Insurrection Act, which gives the president virtually limitless discretion to use the military as a domestic police force. But there are also other ways in which the Posse Comitatus Act fails to provide robust protection against the use of federal troops for law enforcement purposes.

In reality, the principle enshrined in the Posse Comitatus Act is protected more by norms and historical practice than by the text of the law itself. Those norms and practices are significant, to be sure, and efforts to reform the law should embrace and codify them. But in an era in which we can no longer rely on tradition to constrain executive action, the Posse Comitatus Act’s flimsiness poses serious risks. Rather than wait for those risks to materialize, Congress should act now to shore up the law’s protections.

This report proceeds in three parts. Part I discusses the dangers of using the military for domestic law enforcement, a concern that has been prominent in American legal thinking since the nation’s founding. It also explains how the Constitution approaches domestic deployment of the military, including the central role accorded to Congress. Part II lays out the array of problems that undermine the Posse Comitatus Act, from its many statutory exceptions to its lack of meaningful enforcement mechanisms. Finally, part III lays out a legislative proposal for fixing each of these shortcomings.