JP 3-28, page 57

III-1 CHAPTER III SUPPORTING CIVILIAN LAW ENFORCEMENT AGENCIES 1. General a. When requested, federal forces may provide support to federal, state, territory, tribal, insular areas, and local law enforcement organizations reacting to civil disturbances, conducting border security and counterdrug (CD) missions, preparing for antiterrorism operations, and participating in other related law enforcement activities. The requested support must be consistent with the limits Congress placed on military support to law enforcement through the PCA and other laws. b. Upon approval of the governor, state NG forces may support state LEAs within their respective states and within the limits prescribed by state law. State NG forces from another state in state active duty status, or Title 32, USC, operating under the EMAC or a MOA between the states may only support civilian law enforcement as specified in a memorandum approved by both governors. Once federalized, NG forces in Title 10, USC, status have the same restrictions with respect to performing law enforcement functions. 2. The Posse Comitatus Act a. The primary restriction on DOD participation in civilian law enforcement activities is the PCA. The United States Navy (USN) and United States Marine Corps (USMC) are included in this prohibition as a result of DOD policy articulated in DODI 3025.21, Defense Support of Civilian Law Enforcement Agencies. b. IAW DOD policy, unless specifically authorized by law, no DOD personnel in a Title 10, USC, status will become involved in direct civilian law enforcement activities, including, but not limited to, search, seizure, arrest, apprehension, stop and frisk, surveillance, pursuit, interrogation, investigation, evidence collection, security functions, traffic or crowd control, or similar activities, except in cases and under circumstances expressly authorized by the President, Constitution, or act of Congress. “ DOD [Department of Defense] shall be prepared to support civilian LEAs [law enforcement agencies] consistent with the needs of military preparedness of the United States, while recognizing and conforming to the legal limitations on direct DOD involvement in civilian law enforcement activities.” Department of Defense Instruction 3025.21, Defense Support of Civilian Law Enforcement Agencies “Whoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or Air Force as a posse comitatus or otherwise to execute the laws shall be fined under this title or imprisoned not more than two years, or both.” Title 18, United States Code, Section 1385