Posse Comitatus

• 18 USC 1385The Posse Comitatus Act of 1878 / 18 USC Sec 1385:
  “Whoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or the 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.”
• DoD Instruction 3025.01, Defense Support of Civilian Law Enforcement Agencies
• RAND Overview of the Posse Comitatus Act