It's old news, but the President has frequently attached "signing statements" to bills he's signed indicating that, his signature notwithstanding, he won't enforce the law:
Bush has vetoed only one bill since taking office, a bill approved by Congress last week relaxing his limits on federal funding for human embryonic stem cell research. But he has on many occasions signed bills, then issued statements reserving the right not to enforce or execute parts of the new laws, on the grounds that they infringe on presidential authority or violate other constitutional provisions.
Perhaps the most prominent example was legislation last year banning cruel, inhumane or degrading treatment of prisoners at U.S. detention centers. Bush signed the bill into law after a struggle with Congress, then followed it with an official statement indicating that he might waive the ban under his constitutional authority as commander in chief, if necessary to prevent a terrorist attack.
The American Bar Association says that the President can't just say "I'm not enforcing the law" without provoking a constitutional crisis:
"The president is indicating that he will not either enforce part or the entirety of congressional bills," said ABA president Michael S. Greco, a Massachusetts attorney. "We will be close to a constitutional crisis if this issue, the president's use of signing statements, is left unchecked."
The report seemed likely to fuel the controversy over signing statements, which Bush has used to challenge laws including a congressional ban on torture, a request for data on the USA Patriot Act, whistle-blower protections and the banning of U.S. troops in fighting rebels in Colombia.
"The President's constitutional duty is to enforce laws he has signed into being unless and until they are held unconstitutional by the Supreme Court or a subordinate tribunal," [the ABA] panel members wrote. "The Constitution is not what the President says it is."
(Emphasis mine.) It's a bit weaselly, isn't it? He doesn't want to veto something, but he says he simply won't enforce it, which is almost a veto. I'm reminded of President Jackson, after the Supreme Court ordered him not to forcibly move the Cherokee from Georgia, "The Chief Justice has made his decision, now let him enforce it." Not good.