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Government lawyers and privacy advocates lined up Friday morning in front of a federal judge to argue a case brought against a National Security Agency mass-surveillance program.

A group of nine plaintiffs represented by the American Civil Liberties Union is fighting to get over the first hurdle in the lawsuit: convincing Judge T.S. Ellis of the Eastern District Court of Virginia that they have standing to sue the government, a hurdle the ACLU was unable to clear two years ago in a similar case.

The organizations—which include the Wikimedia Foundation, Human Rights Watch, the progressive magazine The Nation, and the conservative Rutherford Institute—want to sue the NSA for violating their Fourth Amendment privacy rights through its "upstream" surveillance program, which scoops up vast amounts of data from critical points on the Internet's physical infrastructure, allowing the agency's analysts access to an enormous database of communications intelligence.

"Americans shouldn't have to worry that the NSA is looking over their shoulder," said the ACLU's Patrick Toomey, the lead plaintiff in the case, outside the courtroom. The constant danger of being followed online has a "chilling effect" on what people read and write on the Internet, Toomey said. "This is the surveillance of the future."

But Toomey will not have a chance to argue the facts of the case unless he and his team can convince the judge that there is evidence their clients are actually being harmed by NSA surveillance.

That's the argument the ACLU tried to make in a 2013 case against NSA spying—and failed. In that case, the Supreme Court ruled that the ACLU and its clients did not have standing to sue because they could not demonstrate that the clients were affected by the government's dragnet. That decision came down just months before Edward Snowden began leaking information about the NSA's programs, and the sheer scale of the surveillance began to come into focus.

The ACLU team hopes that the steady drip of new information about NSA spying since then will push Ellis to green-light their suit this time.

But Justice Department lawyers say this is a rerun of the same story, and they want the judge to dismiss the case. Because the scope and operational details of the NSA's upstream-surveillance program remain classified, the government argued, there is no way for plaintiffs to show proof that their communications were caught up in the NSA's dragnet. Government lawyers condemned as speculation any argument that the NSA "must be" ingesting the plaintiffs' data because of the enormous size of the surveillance operation.

"The plaintiffs two years later cannot get any farther than six of these plaintiffs got two years ago," argued the Justice Department's lead lawyer, Rodney Patton.

The plaintiffs are in a tough position because of the lack of public knowledge about the NSA's work, said Ellis, the federal judge. "How in the world would they get that evidence?" Ellis asked the government lawyer. "This is a very difficult burden for the plaintiff."

But the ACLU lawyers seem convinced they have what they need this time. Citing unclassified government documents like Foreign Intelligence Surveillance Court orders and a 2014 report from the Privacy and Civil Liberties Oversight Board on NSA operations, Toomey argued that "far, far more is known about the surveillance" than was known in 2013.

Further, because the Wikimedia Foundation is a plaintiff this round, the ACLU believes there is no question that the plaintiffs were harmed by spying. Since Wikimedia sends more than a trillion "sensitive internet communications" a year, according to the ACLU's complaint (a number which Patton, the government lawyer, said is out of context), its international communications were bound to have been spied on.

Ellis made no indication of when he will announce his decision on the plaintiffs' standing, but acknowledged the scope and technical nature of the materials both sides submitted for consideration. ("Forests have died for what you've done," he said.)

Although Ellis was presiding over the hearing in Alexandria, Virginia, the case was initially filed in Maryland, where the NSA is based. The Maryland District Court handed the case off because of a peculiar conflict, Toomey said after the hearing: Edward Snowden's mother is an administrator in a Maryland court.

If the judge rules that the case can go forward, Toomey said it would provide a "strong counterpoint" to the outcome of Jewel v. NSA, a case heard in a San Francisco federal court in which the judge ruled that the plaintiffs could not win the case without the declassification of a significant amount of information, which would be harmful to national security.

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