Updated: Dec. 16, 2013, 4:40 p.m. E.T.



The National Security Agency’s program of collecting massive amounts of data about Americans’ phone calls likely violates the Constitution’s protection against unreasonable searches, a federal judge said on Monday.

U.S. District Court Judge Richard Leon ordered the NSA to stop collecting phone records of two plaintiffs who brought the lawsuit, but stayed his own decision while the government appeals, the Associated Press reports. Leon said the government has not proved that collecting so-called metadata about phone calls made prevented any terrorist attacks, Politico reports. He said it likely violates the Fourth Amendment’s ban on unreasonable searches and seizures.

“I cannot imagine a more ‘indiscriminate’ and ‘arbitrary invasion’ than this systematic and high-tech collection and retention of personal data on virtually every single citizen for purposes of querying it and analyzing it without judicial approval,” Leon wrote in his 68-page ruling, according to Politico.

It’s the first major legal setback to the NSA’s mass-surveillance program since details of the program were leaked by former NSA contractor Edward Snowden.

In a statement published in the New York Times, Snowden said the ruling would likely be the first of many. “I acted on my belief that the NSA’s mass-surveillance programs would not withstand a constitutional challenge, and that the American public deserved a chance to see these issues determined by open courts,” Snowden said. “Today, a secret program authorized by a secret court was, when exposed to the light of day, found to violate Americans’ rights. It is the first of many.”

Leon’s ruling was made in a lawsuit brought by Larry Klayman, a conservative legal activist.

“I have significant doubts about the efficacy of the metadata-collection program as a means of conducting time-sensitive investigations in cases involving imminent threats of terrorism,” Leon wrote. “The government does not cite a single instance in which analysis of the NSA’s bulk metadata collection actually stopped an imminent attack, or otherwise aided the government in achieving any objective that was time-sensitive in nature.”

This story was updated to include the statement from Snowden. It was distributed to the New York Times by journalist Glenn Greenwald, who wrote the first story about Snowden’s documents.