what did the posse comitatus act do?
Posse Comitatus Act. The Posse Comitatus Act is a United States federal law (18 U.S.C. Â§ 1385, original at 20 Stat. 152) signed on June 18, 1878 by President Rutherford B. Hayes. The purpose of the act â in concert with the Insurrection Act of 1807 â is to limit the powers of the federal government in using federal military personnel to enforce domestic policies within the United States.