The President later acknowledged that in the weeks following September 11, he authorized a “terrorist surveillance program to detect and intercept al Qaeda Communications” and stated that the program applied “only to international communications, in other words, [where] one end of the communication [was] outside the United States.”

...The complaints “challenge[d] the legality of Defendants’ participation in a secret and illegal government program to intercept and analyze vast quantities of Americans’ telephone and Internet communications.”

While the complaints were pending, and at least in part due to them,

...Congress enacted the FISA Amendments Act of 2008... Among the amendments is § 802, an immunity provision and related procedures that are triggered if the United States Attorney General certifies to one or more of five conditions. In such case, no civil action may be maintained “against any person for providing assistance to an element of the intelligence community.”

...Section 802(a) permits the Attorney General to certify to a court that assistance was provided under at least one of a series of situations—ranging from a Foreign Intelligence Surveillance Court order, a national security letter, an Attorney General directive regarding FISA-authorized warrantless surveillance to participation in the TSP—or that no assistance was provided.

This certification is subject to judicial review under a substantial evidence standard: “[a] certification under subsection (a) shall be given effect unless the court finds that such ertification is not supported by substantial evidence provided to the court pursuant to this section.” § 802(b)(1).

Rejecting a due process challenge, the Court says:

[W]e conclude that the procedures afforded under § 802 are sufficient under the Due Process Clause. Given the circumstances dictated by national security concerns, the statute provides sufficient notice of a range of grounds for immunity from suit and provides meaningful judicial review based on substantial evidence.

The 9th Circuit also found no Separation of Powers violation. In sum,

[W]e conclude that the statute is constitutional and does not violate Articles I or III of the Constitution or the Due Process Clause of the Fifth Amendment.

More information on the lawsuit is available at EFF, which represented the lead plaintiff.