This was discussed on All Things Considered today. The power of the gov to therecords was adjudicated decades ago in favor of the gov. The favoring argument (as I understand it) is that the records of calls are already in the hands of a third party, the phone company, so there is no expectation of privacy. The phone company does not have that same possession of the conversation so the conversation is protected under the assumption of expectation of privacy. So, the gov must obtained a warrant from a judge to tap a conversation but a simple order is all that is needed for phone records.

I first learned of this watching "Law and Order", in which Lenny told the perp he was going to get the records anyway as they are not protected by law. So between the Supreme Court upholding it and Lenny claiming it, I think the gov is on legally safe ground.

But is it "right?" That's a whole 'nuther question.