In a nutshell, this act bans the Army, Navy, Air Force and Marines from participating in arrests, searches, seizure of evidence and other police-type activity on U.S. soil. The Coast Guard and National Guard troops under the control of state governors are excluded from the act.
Amend Posse Comitatus for natural disaster situations, if it hasn't been already!
CHAP. 263 - An act making appropriations for the support of the Army for the fiscal year ending June thirtieth, eighteen hundred and seventy-nine, and for other purposes.
SEC. 15. From and after the passage of this act it shall not be lawful to employ any part of the Army of the United States, as a posse comitatus, or otherwise, for the purpose of executing the laws, except in such cases and under such circumstances as such employment of said force may be expressly authorized by the Constitution or by act of Congress; and no money appropriated by this act shall be used to pay any of the expenses incurred in the employment of any troops in violation of this section And any person willfully violating the provisions of this section shall be deemed guilty of a misdemeanor and on conviction thereof shall be punished by fine not exceeding ten thousand dollars or imprisonment not exceeding two years or by both such fine and imprisonment.
10 U.S.C. (United States Code) 375
Sec. 375. Restriction on direct participation by military personnel:
The Secretary of Defense shall prescribe such regulations as may be necessary to ensure that any activity (including the provision of any equipment or facility or the assignment or detail of any personnel) under this chapter does not include or permit direct participation by a member of the Army, Navy, Air Force, or Marine Corps in a search, seizure, arrest, or other similar activity unless participation in such activity by such member is otherwise authorized by law.
18 U.S.C. 1385
Sec. 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.
Editor's Note: The only exemption has to do with nuclear materials (18 U.S.C. 831 (e)