If we’ve never had a scandal like this before, it’s in part because it is legally dubious. Federal law bars phone carriers from handing over records without an individual’s agreement. The statute makes some exceptions, including for federal and state law-enforcement agencies.

But not for lawmakers. “There does not appear to be any basis to believe that a congressional committee is authorized to subpoena telephone records directly from a provider—as opposed to an individual,” former Attorney General Michael Mukasey tells me.

Maybe that’s because no one would have conceived of Congress needing to peruse private phone records. Its mission is writing laws. Or it might have been in recognition that Congress has no outside check on its subpoena powers. Law-enforcement subpoenas generally entail court supervision, helping to ensure they have a valid purpose. Mr. Schiff, working in secret, unilaterally decided he was entitled to see the phone records of private citizens.