JP 3-28, page 58

Chapter III III-2 JP 3-14 c. These restrictions also apply to reserve members of the United States Army (USA), USN, United States Air Force (USAF), and USMC who are on active duty, active duty for training, or inactive duty training in a Title 10, USC, duty status. d. The PCA does not apply to NG forces operating in state active duty or Title 32, USC, status. However, when the NG is operating under a Title 10, USC, status (federal status), they are subject to the PCA. The PCA does not restrict the USCG, even when operating under the USN, due to the USCG having inherent law enforcement authority under Title 14, USC. e. Since commanders’ initial uncertainty regarding the nature and extent of PCA restrictions may cause delays in what would be appropriate employment of federal forces, it is imperative that commanders likely to be assigned DSCA missions gain familiarity with such provisions. 3. Direct Assistance to Civilian Law Enforcement Agencies a. Permissible Direct Assistance (1) Military Purpose. There are several forms of direct assistance to civilian law enforcement by military personnel that are permitted under the Military Purpose Doctrine. The Military Purpose Doctrine provides that law enforcement actions that are performed primarily for a military purpose, even when incidentally assisting civil authorities, will not violate the PCA. The Military Purpose Doctrine requires a legitimate, independent military purpose for participating in law enforcement activities against civilians. DODI 3025.21, Defense Support of Civilian Law Enforcement Agencies, provides guidance on the type of assistance DOD can provide to local authorities when it is primarily for a military purpose and does not violate the PCA. Support provided to civilian law enforcement must be incidental. DOD cooperation with civilian law enforcement officials includes: (a) Investigations and other actions related to the enforcement of the Uniform Code of Military Justice. (b) Investigations and other actions related to the commander’s inherent authority to maintain law and order on a military installation or facility. (c) Protection of classified military information or equipment. (d) Protection of DOD personnel, DOD equipment, and official guests of DOD. (e) Other actions that are undertaken primarily for a military or foreign affairs purpose. (2) Emergency Authority. Emergency authority should not be confused with immediate response authority. Federal forces acting under immediate response authority are still bound by the PCA and may not participate directly in law enforcement. Emergency