Here is how Paul Butler, a former federal prosecutor and a special assistant to Donald Rumsfeld at the Pentagon, defends the Bush administration against the charge that it avoids legal challenges to its anti-terrorism policies by switching tactics at the last minute:
You do have to ascribe some good faith. The government uses presidential authority when they think it's necessary and the law does not provide the specific authority they need. If there is a road that can be taken, operating according to statutes or putting people into the criminal justice system when that makes sense, they will do that.
So the president is happy to follow the law as long as it gives him the authority he wants. He goes outside the law only when he thinks it's necessary. This is called "good faith."
The really sad thing is that Bush does not seem to meet even this pathetically low standard. For years he had the National Security Agency violate the Foreign Intelligence Surveillance Act by monitoring international communications of people on U.S. soil without warrants, supposedly because getting court approval would have been too cumbersome. This week, with court challenges and congressional hearings pending, his administration announced that the necessary surveillance can be conducted lawfully after all.