It turns out that telephone billing records are virtually public information, according to Powerline:

UPDATE: Maybe I’m the only one who didn’t already know this, but I was astonished to learn that there is no expectation of privacy in telephone records at all. Section 2702(c) sets out the circumstances in which a telecom provider can disclose phone records, not including the contents of communications. So this would cover the call information at issue in this program. 2702(c)(6) says that such phone records may be freely disclosed, at the company’s discretion:

(6) to any person other than a governmental entity.

That’s right. These supposedly top-secret telephone records can be given or, more likely, sold to any company or private citizen. So if I had enough money, I could buy the phone records of every person in the U.S., and donate them to the NSA.

Suppose the NSA was asked to analyze calling patterns from the CIA to the New York Times and Washington Post. That might point to potential leakers. Take it a step futher and see which private numbers are calling both the CIA and one or other of the papers. The final step is to see which of those private numbers are calling each other.

Suppose Ms. Lucy Leaker at the CIA wants to tell Mr. Ace Reporter about a new Bush plot to enslave Americans. She might call Ace from her CIA office at his NYT office and say she’s got something to tell him, and to call her privately. Ace goes home and calls Lucy on her cell phone. So far, you’d have two unconnected phone calls. But Ace calls into his office on the same phone, and Lucy does likewise. A few database queries later you’d know that Lucy and Ace are talking way too much, which might explain why Ace’s scoops are based on highly classified programs that Lucy knows about. At that point it may be possible to get warrants to tap their phones and otherwise monitor their communications.

Scary thought? Not to me, because I believe the current crop of leakers are traitors and should be treated accordingly. But it sure must be a worry to leakers and the reporters they talk to.