Infowars - Section 1385 of the Posse Comitatus Act states, "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."
Under the John Warner Defense Authorization Act, signed by President Bush on October 17, 2006, the law was changed to state, "The President may employ the armed forces to restore public order in any State of the United States the President determines hinders the execution of laws or deprives people of a right, privilege, immunity, or protection named in the Constitution and secured by law or opposes or obstructs the execution of the laws of the United States or impedes the course of justice under those laws."
However, these changes were repealed in their entirety by HR 4986: National Defense Authorization Act for Fiscal Year 2008, reverting back to the original state of the Insurrection Act of 1807.
The original text of the Insurrection Act severely limits the power of the President to deploy troops within the United States.
For troops to be deployed, a condition has to exist that, "(1) So hinders the execution of the laws of that State, and of the United States within the State, that any part or class of its people is deprived of a right, privilege, immunity, or protection named in the Constitution and secured by law, and the constituted authorities of that State are unable, fail, or refuse to protect that right, privilege, or immunity, or to give that protection; or (2) opposes or obstructs the execution of the laws of the United States or impedes the course of justice under those laws. In any situation covered by clause (1), the State shall be considered to have denied the equal protection of the laws secured by the Constitution."