18 U.S.C. § 1385 : US Code - Section 1385: Use of Army and Air Force as posse comitatus

      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.