Bush's defenders have portrayed his actions with signing statements as standard operating procedure for all recent presidents. In particular, they have cited Presidents Reagan, George H.W. Bush, and Clinton's signing statement practices as precedents. But Bush's use of the signing statement is not only non-standard, it is egregious, and plainly itself unconstitutional.
The Constitution, and the president's oath of office swearing to uphold it, require a president to veto legislation he finds unconstitutional, and send it back to Congress so its members can correct the flaw. The system is simple and wise - and Bush is subverting it.
In over six years in office, Bush has not vetoed a single bill. Therefore, he has avoided the political costs those vetoes would have rightly entailed. Instead, Bush has issues a steady stream of signing statements claiming that the very bills he is signing have constitutional problems.
Bush's extraordinary and unconstitutional use of signing statements is making the laws enacted by the representatives of the people irrelevant. It is also making a mockery of due process: How can anyone have prior notice of what the law says, if so many laws come with a warning that the President may disregard some of their provisions?