In October 2006, Bush signed into law the John Warner National Defense Authorization Act for Fiscal Year 2007, (also known under the title Department of Defense Authorization Act for Fiscal Year 2007) [The John Warner NDAA 07 was adopted on 17 October 2006]
NDAA 07 includes specific provisions which allow the military to take control of normal policy and law enforcement functions at the Federal and State levels.
Sec. 1076 of the NDAA 07 overturns the Posse Comitatus Act of 1878, which prevents the military from intervening in the conduct of civilian government activities, including the conduct of Justice and Law Enforcement. Posse Comitatus has been central to the functioning of constitutional government. (It should be noted that other previous pieces of legislation have already invalidated the substance of Posse Comitatus).
What is significant in these specific provisions of NDAA 07 (Sec. 1076) is that they dovetail the provisions of Bush's National Security Presidential and Homeland Directive (NSPD 51, HSPD 20) enacted on May 9, 2007.
NSPD 51 would essentially scrap Constitutional government in the case of a so-called "Catastrophic Emergency". .