Sending in soldiers to effect an arrest would have violated this law: The Posse Comitatus Act is a United States federal law (18 U.S.C. § 1385) passed on June 18, 1878, after the end of Reconstruction, with the intention (in concert with the Insurrection Act of 1807) of substantially limiting the powers of the federal government to use the military for law enforcement. The Act prohibits most members of the federal uniformed services (today the Army, Air Force, and State National Guard forces when such are called into federal service) from exercising nominally state law enforcement, police, or peace officer powers that maintain "law and order" on non-federal property (states and their counties and municipal divisions) within the United States. The statute generally prohibits federal military personnel and units of the National Guard under federal authority from acting in a law enforcement capacity within the United States, except where expressly authorized by the Constitution or Congress. The Coast Guard is exempt from the Act during peacetime. The only time to bring in soldiers is when normal law enforcement is unequal to the danger or the task. Ba'al Chatzaf The Posse Comitatus Act is no more. Safety from external danger is the most powerful director of national conduct. Even the ardent love of liberty will, after a time, give way to its dictates. The violent destruction of life and property incident to war, the continual effort and alarm attendant on a state of continual danger, will compel nations the most attached to liberty to resort for repose and security to institutions which have a tendency to destroy their civil and political rights. To be more safe, they at length become willing to run the risk of being less free. ~ Federalist Paper No. 8, in which Alexander Hamilton displayed an atypical ardor to defend liberty against state power. "this is Nero at his worst. The Constitution is gone." Those were the trenchant words spoken extemporaneously when Justice James Clark McReynolds read his dissent from the bench U.S. Supreme Court U.S. v. BANKERS' TRUST CO., 294 U.S. 240 (1935) The Posse Comitatus Act prohibits the use of any part of the Army, Air Force, Navy, or Marines, including their reserve components, as a posse comitatus ("armed force") or otherwise to execute the laws, except as authorized by the Constitution or Act of Congress. Congress has created a number of statutory exceptions to the Posse Comitatus Act, which fall into four major categories: (1) insurrections and civil disturbances, [4] (2) counterdrug operations, [5] (3) disaster relief, [6] (4) counter-terrorism and weapons of mass destruction."