Glenn Greenwald gives us an important history lesson. In 2002, Republicans in Congress sought to allow wire tapping under FISA of non-U.S. citizens based on "reasonable suspicion" rather than "probable cause". Yesterday, you may remember, it was the distinction between "probable cause" and "reasonable suspicion" that forced the administration into an end-run around the FISA process.
The Bush administration opposed the change.
Why?
One possible reason is that the Bush administration really doesn't want to have to deal with the FISA courts at all because they are an inconvenience on executive authority.
More likely, though, is this: Congressional action to amend the FISA rules in 2002 would have put the lie to any claim that the president had inherent war authority to circumvent visa post-September 11. Further, the 2002 amendment only applied to non-U.S. citizens and the Bush administration really wanted to eavesdrop on Americans.
Why else would the Bush administration prefer to operate in a murky Constitutional area rather than under clear, manageable, Congressional authority?