I would imagine those whose records were obtained would have a civil case against the phone carriers. I think Schiff is only immune from libel laws if he is speaking in the well of the House. I don’t believe he is immune from criminal prosecution if the subpoenas were illegal on their face.
I also don’t think he’s immune from a Federal Civil Rights violation for improperly receiving the phone records.
I suppose the best scenario to take that pencil-necked geek down would be to file a lawsuit against the phone carriers, then ask for discovery to establish who signed off on the subpoenas and go back from there.
You would need someone like Tom Fitton and Judicial Watch to have the expertise to take on a case like this. I wonder if he’d be willing to pursue it?
My personal thought is why go to the trouble, expense and long time. There are easier and very permanent methods for dealing with schiff