In late December when the President signed McCain's widely popular anti-torture bill his signing statement gave some serious doubts as to whether he took it seriously.
The executive branch shall construe Title X in Division A of the Act, relating to detainees, in a manner consistent with the constitutional authority of the President to supervise the unitary executive branch and as Commander in Chief and consistent with the constitutional limitations on the judicial power, which will assist in achieving the shared objective of the Congress and the President, evidenced in Title X, of protecting the American people from further terrorist attacks.
Further, in light of the principles enunciated by the Supreme Court of the United States in 2001 in Alexander v. Sandoval, and noting that the text and structure of Title X do not create a private right of action to enforce Title X, the executive branch shall construe Title X not to create a private right of action.
Bush is announcing two things: first, that Congress's law prohibiting torture will be secondary to "protecting the American people from further terrorist attacks". Since this was his original reason for the prisoner-torturing that McCain's law is trying to prevent, Bush is basically saying this wouldn't have prevented him from doing what he did and it's not going to prevent him from doing it again. Secondly, he's saying that because the law only says "torture is bad" and not "what you can do about it" there is no "private right of action". In other words even if you get tortured by the President you still can't sue him, the torturers, or the US government.
Signing statements were fairly uncommon in the past because past presidents didn't need to state how they would choose to comply with the laws that Congress passed . From President Monroe's administration (1817-25) to the Carter administration (1977-81) the executive branch issued a total of 75 signing statements to protect presidential prerogatives. From Reagan's administration through Clinton's the total number of signing statements by all presidents was 247, or 50 per term. Bush has issued at least 435 signing statements in his first term alone.
It's also worth noting the Unitary Executive theory that Bush invokes four times in his torture signing bill. Unitary Executive Theory claims that "the President has the power to interpret the law as it applies to the actions of the executive branch, in the absence of judicial determination", or more simply "a law means what the President says it means, not what the Congress says it means". For example in signing the Foreign Relations Authorization Act of 2003 he said:
The executive branch shall construe as advisory the provisions of the Act ... that purport to direct or burden the conduct of negotiations by the executive branch ... Such provisions, if construed as mandatory rather than advisory, would impermissibly interfere with the President's constitutional authorities to conduct the Nation's foreign affairs, participate in international negotiations, and supervise the unitary executive branch.
In other words "you made laws saying what the Executive Branch can do but we're not going to do those things because they interfere with us doing things we say the constitution lets us do". He's used this argument 95 times, from torture of prisoners to negotiating treaties with other countries to flouting the FISA law requiring warrants for wiretaps. The chutzpah required to say "I'm not going to follow the law I am signing" boggles my mind - if you're not going to follow the law then that's what the veto is for, isn't it?