Insurrection Act

The Insurrection Act of 1807 is a United States federal law that empowers the president of the United States to deploy U.S. military and federalized National Guard troops within the United States in particular circumstances, such as to suppress civil disorder, insurrection, or rebellion. The act provides a "statutory exception" to the Posse Comitatus Act of 1878, which limits the use of military personnel under federal command for law enforcement purposes within the United States. Before invoking the powers under the Act, requires the President to first publish a proclamation ordering the insurgents to disperse. As part of the Posse Comitatus Act of 1878, these provisions have since been amended. There are Constitutional exceptions to Posse Comitatus restrictions rooted in the president's own constitutional authority. Defense Department guidelines describe "homeland defense" as a "constitutional exception" to Posse Comitatus restriction, meaning that measures necessary to guarantee National Security from external threats are not subject to the same limitations.