President Bush has signed into law a provision which, according to Senator Patrick Leahy (D-Vermont), will actually encourage the President to declare federal martial law. It does so by revising the Insurrection Act, a set of laws that limits the President’s ability to deploy troops within the United States. The Insurrection Act (10 U.S.C.331 -335) has historically, along with the Posse Comitatus Act (18 U.S.C.1385), helped to enforce strict prohibitions on military involvement in domestic law enforcement. With one cloaked swipe of his pen, Bush is seeking to undo those prohibitions.
[A]llows the President to declare a "public emergency" and station troops anywhere in America and take control of state-based National Guard units without the consent of the governor or local authorities, in order to "suppress public disorder."
You thought that torture bill was bad – that same day this got signed: