Posse Comitatus Act

Sign in to your account.

Status Brief

Developmental Milestones/Developments to Date:

Current Assessment/State of the Field:




Winthrop, Jim, “The Oklahoma City Bombing: Immediate Response Authority and Other Military Assistance to Civil Authority (MACA),” Army Lawyer, July 1993.

  1. “Military support to Civil Authority refers primarily to natural disaster relief…”

Stafford Act, Federalism, Police Powers, FEMA, DoD Directives 3025.15, 3025.1, Military, Posse Comitatus Act


Gilligan, Major Matthew J.,Opening the Gate?: An Analysis of Military Law Enforcement Authority Over Civilian Lawbreakers On and Off the Federal InstallationMILITARY LAW REVIEW, Volume 161, September 1999.

  1. “Military commanders have the inherent authority and duty to maintain law and order on military installations and to guarantee the security of the occupants thereon.”
  2. “Congress has specifically granted to military law enforcement officials statutory arrest authority over service members for violations of the Uniform Code of Military Justice.”
  3.  The Posse Comitatus Act “prohibits using military personnel to execute civil laws unlss authorized by the Constitution or an Act of Congress.”
  4.  Exceptions to the Posse Comitatus Act include the Military Purpose Doctrine and a service member assisting as a private citizen.

Military, Posse Comitatus Act, Military Purpose Doctrine, Uniform Code of Military Justice, Law Enforcement, Law


Yoo, John C. and Robert J. Delahunty, “Authority for Use of Military Force to Combat Terrorist Activities Within the United States,” OFFICE OF LEGAL COUNCIL, October 23, 2001.

  1.  Posse Comitatus “only applies to the domestic use of the Armed Forces for law enforcement purposes, rather than for the performance of military function.” Exception: “allows the use of military when constitutionally or statutorily authorized.”
  2.  Constitution “supports deployment of the military domestically, as well as abroad, to respond to attacks on the US.”
  3.  PCA “intended to prevent the use of the military for domestic law enforcement purposes. It does not address the deployment of troops for domestic military operations against potential attacks on the US.”

 Posse Comitatus Act, Law Enforcement, Military


Bolgiano, David G., “Military Support of Domestic Law Enforcement Operations: Working Within Posse Comitatus,” FBI LAW ENFORCEMENT BULLETIN, December 2001, Volume 70, Issue 12, page 16.

  1. Legal issues from law enforcement/military overlap
  2. “encounter military support in counterdrug operations, training, disaster assistance, or search and rescue missions.”
  3. “police officers protect the public safety by investigating criminal activity while the military fights the battles against hostile enemies.”

 Posse Comitatus Act, Law Enforcement, Military


Lecchire, Gary, and Michael A. Wermuth, et al., “Triage for Civil Support: Using Military Medical Assets to Respond to Terrorist Attacks“, TRIAGE, “Legal and Other Barriers to Military Support to Civil Authorities“, 2004.

  1. “State governments and their political subdivisions have primary responsibility for coping with emergencies, including terrorist events.”
  2. Military support for civil authorities, 4 categories allowed: ‘civil disturbance/insurrections, counterdrug operations, disaster relief, counterterrorism/weapons of mass destruction.’
  3. “Under the Stafford Act, a presidential declaration of a major disaster or an emergency triggers federal assistance. The type of federal assistance available depends on whether the situation is considered a disaster or an emergency.”
  4. “In the event of a catastrophic event, particularly when a deadly biological agent is implicated, officials, including military personnel, may need to restrict the civil liberties of Americans, especially freedom of movement, to prevent mass chaos and mitigate public health threats.”

Stafford Act, Public Health, Emergency Response, Posse Comitatus Act, Law Enforcement, Military


Elsea, Jennifer, “The Posse Comitatus Act and Related Matters: A SketchCRS REPORT FOR CONGRESS, June 6, 2005.

  1. prevent the use of military as law enforcement unless authorized by Congress or Constitution
  2. “bills that could result in increased interaction between military and civilian authorities” (H.R. 1986, H.R. 1815, S. 1042, S. 1043)

 Posse Comitatus Act, Law Enforcement, Military


Elsea, Jennifer, “The Use of Federal Troops for Disaster Assistance: Legal Issues“, CRS REPORT FOR CONGRESS, September 16, 2005.

  1. The Stafford Act, The Insurrection Act
  2. shared information between military and law enforcement

 Posse Comitatus Act, Law Enforcement, Military


Pine, Art. “Should Congress Scrap Posse Comitatus?U.S. Naval Institute Proceedings. December 2005. Last Checked. September 9, 2012

  1. ”Posse Comitatus is not the only governing statute on this issue, however. The 1974 Stafford Act broadly permits the president to use federal troops at home whenever he declares a disaster to be “an incident of national significance” — something Bush did the Saturday before Katrina struck.”
  2. “The 1956 Insurrection Act enables him to send U.S. forces to deal with civil disorders, even without a request from a state’s governor. And other titles permit the White House to send troops to deal with emergencies involving nuclear, chemical, or biological weapons. The Pentagon, too, has directives that authorize such action.”
  3. ”Eventually, the military response to Katrina included about 50,000 National Guard troops, 22,000 active-duty forces, about 350 military helicopters, and 20 ships. The flaw was in how long it took to get permission for them to deploy.”
  4. ”Some say the 1878 law is a relic of a different age that ties the hands of the military during natural disasters and should be repealed or revised. Others say that the statute still serves an important purpose. Meanwhile, paratroopers from the Army’s 82d Airborne Division (at left) were assisting civilian search-and-rescue personnel after Hurricane Katrina.”
  5. ”Few question that the military is best equipped to cope with major calamities such as Katrina when the impact spreads beyond what state and local agencies can handle. The armed forces already have a broad command structure and communications system in place, with an array of helicopters, trucks, and medical facilities, along with sufficient manpower to quell civil disorders.”
  6. ”Indeed, a recent study cited some 167 incidents over the past 200 years in which presidents have used federal troops to enforce the law, from suppressing insurrections and quelling race riots to breaking strikes and enforcing civil rights legislation.”

 Posse Comitatus Act, Law Enforcement, Military, Emergency Response


Baker, Al, “When the police go military,New York Times, December 3, 2011, http://www.nytimes.com/2011/12/04/sunday-review/have-american-police-become-militarized.html?scp=1&sq=posse%20comitatus&st=cse, Last Checked February 4, 2012.

  1. ”Lately images from Occupy protests streamed on the Internet — often in real time — show just how readily police officers can adopt military-style tactics and equipment, and come off more like soldiers as they face down citizens. Some say this adds up to the emergence of a new, more militaristic breed of civilian police officer.”
  2. ”Both wars — first on drugs, then terror — have lent police forces across the country justification to acquire the latest technology, equipment and tactical training for newly created specialized units.”
  3. “And then the problem is, if you have those kinds of specialized units, that you hunt for appropriate settings to use them and, in some of the smaller police departments, notions of the appropriate settings to use them are questionable.”
  4. ”The Posse Comitatus Act of 1878 generally bars the military from law enforcement activities within the United States. But today, some local and city police forces have rendered the law rather moot. They have tanks — yes, tanks, often from military surplus, for use in hostage situations or drug raids — not to mention the sort of equipment and training one would need to deter a Mumbai-style guerrilla assault.”
  5. ”More disturbing than riot gear or heavy-duty weapons slung across the backs of American police officers is a ‘militaristic mind-set’ creeping into officers’ approach to their jobs, said Timothy Lynch, director of the criminal justice project at the Cato Institute, a libertarian think tank.”
  6. ”’What is most worrisome to us is that the line that has traditionally separated the military from civilian policing is fading away,’ Mr. Lynch said. ‘We see it as one of the most disturbing trends in the criminal justice area — the militarization of police tactics.’ “
  7. ”Police officials insist they are not becoming more militarized — in their thinking or actions — but merely improving themselves professionally against evolving threats. This is the way to protect citizens and send officers home alive at the end of shifts in an increasingly dangerous world, they say.”
  8. ”Now the Occupy movement and highly publicized official responses to it are forcing the public to confront what its police forces have become.”

 Posse Comitatus Act, Law Enforcement, Military