There's certainly a good case to be made for adjusting the FISA provisions. The problem is that the normal benefit of the doubt one would like to extend to an administration cannot be extended to this one.
Just today, even as the House voted to trust Bush one more time, his former press spokesman was in a nearby hearing room outlining all the ways the administration lied, shaded the truth, overstated intel and generally demonstrated that trust was undeserved.
The immunity provision is the rub. There seems to be no other mechanism to hold the lawbreaking accountable other than civil lawsuits, considering that Congress apparently is helpless to do it's oversight job. The sad thing is that Congress, while unable or unwilling to do its job, is more than willing to stop anyone else from doing it either.