The following documents have been released regarding how the military can "help" during certain civilian disturbances.
Convergence: Special Operations Forces and Civilian Law Enforcement, July 2010 by Dr. John Alexander [123 Pages, 3.7 MB] - John B. Alexander’s monograph about the convergence of Special Operations Forces (SOF) and civilian law enforcement activities is timely considering the U.S. Government’s revamped strategies to promote more capable and effective governments and improve security in southwest Asia. The strategic concept includes fully resourcing security training for military and police forces. U.S. strategic objectives envision two outcomes: a) governments that can provide effective internal security with limited international support and b) military and police security forces that can lead the counterinsurgency and counterterrorism fight with reduced U.S. assistance.
Defense Support of Civil Authorities, 16 May 2008 [570 Pages, 41.2 MB] - Natural or man-made disasters and special events can be so demanding that local, tribal, state and non-military federal responders are temporarily overwhelmed by the situation. The Department of Defense (DOD) has a long history of supporting civil authorities in the wake of catastrophic events. When directed by the President or the Secretary of Defense (SecDef), United States Northern Command (USNORTHCOM} will respond quickly and effectively to the requests of civil authorities to save lives prevent human suffering, and mitigate great property damage. The Joint Strategic Capabilities Plan 2008 (JSCP) directs CDRUSNORTHCOM to prepare a plan to support the employment of Title 10 DOD forces providing Defense Support of Civil Authorities (DSCA) in accordance with (lAW) the National Response Framework (NRF), applicable federal law, DOD Directives (DODD), and other policy guidance including those hazards defined by the National Planning Scenarios that are not addressed by other JSCP tasked plans. DSCA is a subset of DOD civil support that is performed within the parameters of the NRF.
March 10, 2009, Alabama MPs were sent from Ft. Rucker to the streets of Alabama to assist after a murder spree [14 Pages, 479k] - Although not directly related to Garden Plot, I feel that this set of documents is best suited here. Many have theorized this incident was a violation of federal law. In a FOIA request to the Army, I was able to obtain all documents associated with this incident, along with the memorandum of understanding between Ft. Rucker and the Sheriff's department of the area.
Military Police Internment / Resettlement Operations, FM 3-19.40 [235 Pages, 16.93 MB] - Army Field Manual FM 3-19.40: Military Police Internment/Resettlement Operations. Military Handbook for Police Internment and Resettlement Operations. Field Manual depicts the doctrinal foundation, principles, and processes that Military Police will employ when dealing with enemy prisoners of war, civilian internees etc. Provides that the provisions of the Geneva Conventions are applicable to captives and detainees from the time they are captured until they are released or repatriated. . . . Detainees receive humane treatment... captives and detainees are not murdered, mutilated, tortured, or degraded."
Operation Garden Plot
Operation Garden Plot is a general U.S. Army and National Guard plan to respond to major domestic civil disturbances within the United States. The plan was developed in response to the civil disorders of the 1960s and is now under the control of the U.S. Northern Command (NORTHCOM). It provides Federal military and law enforcement assistance to local governments during times of major civil disturbances.
Department of Defense Civil Disturbance Plan (Operation Garden Plot) [253 Pages, 400k]
Operation Garden Plot [146 Pages]
U.S. Army Field Manual 3-19.15 Civil Disturbance Operations [256 Pages]