In 2013, the Supreme Court rejected a challenge to a once-clandestine warrantless surveillance program that gobbles up Americans' electronic communications—a project secretly adopted in the wake of the 2001 terror attacks on the United States. Congress legalized the surveillance in 2008 and again in 2012 after it was exposed by The New York Times.

Human-rights activists and journalists brought the Supreme Court challenge amid claims that the FISA Amendments Act was chilling their speech. But the Supreme Court tossed the case, telling the challengers' lawyers from the American Civil Liberties Union to bring proof by real targets of the warrantless e-mail and phone surveillance. In a 5-4 ruling (PDF) by Justice Samuel Alito at the time, the court said the case was based on "assumptions" and that the plaintiffs "merely speculate" that they were being spied upon.

Fast forward to the present day: a US resident of Brooklyn, New York, accused of sending $1,000 to a Pakistani terror group has won the right to become the nation's second defendant to challenge the surveillance at the appellate level. This could mean a Supreme Court bid is likely several months or more away.

Agron Hasbajrami, 31, is one of five US citizens or residents identified by the Justice Department as having prosecutions built upon the warrantless surveillance of their electronic communications. Hasbajrami, also an Albanian citizen, pleaded guilty Friday to the terror charges. He faces 15 years or more in prison. The plea deal allows him to challenge the warrantless surveillance of his e-mails to the 2nd US Circuit Court of Appeals, and his attorneys have vowed such an appeal.

The FISA Amendments Act currently allows US spies to vacuum up e-mail and phone calls of Americans without a probable-cause warrant. One of the parties to the communications must be believed to be outside the United States. The authorities may undertake this surveillance "to acquire foreign intelligence information." Although no Fourth Amendment probable cause warrant is required, the Foreign Intelligence Surveillance Court (FISA Court) must give its blessing to the surveillance. That blessing, however, is largely a rubber stamp.

The authorities needn't say who is being targeted, and the surveillance can begin a week before the request is made. Also, if the FISA court rejects the request, the government may continue the monitoring during the appellate process.

"This case, like many others before it, has shown that the application of lawful surveillance can allow the United States government to detect and disrupt a terrorist in the United States,” acting Brooklyn US Attorney Kelly Currie said. "The defendant’s plea today leaves no question as to his role in a very serious terrorism offense, and if he chooses to bring an appeal, we are confident we will prevail in the appellate court as well."

US District Judge John Gleeson in Brooklyn had denied Hasbajrami's bid to suppress the e-mail evidence used against him. The judge ruled that the surveillance was approved by the FISA Court and said the surveillance program had "extensive oversight" by Congress.

The only other known terror defendant convicted under the warrantless surveillance program whose case is on appeal is Mohamed Osman Mohamud. He was sentenced to 30 years in prison last year and was convicted in a FBI sting operation of attempting to ignite what he thought was a bomb at a Christmas tree lighting ceremony in Portland, Oregon.

That case is pending before the 9th US Circuit Court of Appeals.