"That order grants Yahoo immunity, said Albert Gidari, director of privacy at Stanford University's Center for Internet and Society. "I think it is pretty clear that if Yahoo rendered technical assistance to the government pursuant to a FISA order or directive, it faces no liability for doing so and is immunized for doing so," Gidari said in an email.
Yahoo users upset about unwarranted email surveillance have another problem: standing. Under U.S. Supreme Court precedent, plaintiffs have to show a concrete injury. At this point, there aren't enough details to show an injury to particular plaintiffs, Gidari said.
Yahoo could be sued in state court for deceptive practices, Gidari said, since publicly it has opposed U.S. government information requests. "But again, the immunity provided under FISA is complete and I'm afraid the liability may consist more of public disappointment and changing email providers," he says."