(Reuters) - A federal appeals court on Tuesday revived a Wikipedia lawsuit that challenges a U.S. National Security Agency (NSA) program of mass online surveillance, and claims that the government unconstitutionally invades people’s privacy rights.

A man is silhouetted near logos of the U.S. National Security Agency (NSA) and Wikipedia in this photo illustration taken in Sarajevo March 11, 2015. REUTERS/Dado Ruvic/File Photo

By a 3-0 vote, the 4th U.S. Circuit Court of Appeals in Richmond, Virginia, said the Wikimedia Foundation, which hosts the Wikipedia online encyclopedia, had a legal right to challenge the government’s Upstream surveillance program.

The decision could make it easier for people to learn whether authorities have spied on them through Upstream, which involves bulk searches of international communications within the internet’s backbone of cables, switches and routers.

Upstream’s existence was revealed in leaks by former NSA contractor Edward Snowden in 2013.

Lawyers for the Wikipedia publisher and eight other plaintiffs including Amnesty International USA and Human Rights Watch, with more than 1 trillion international communications annually, argued that the surveillance violated their rights to privacy, free expression and association.

The U.S. Department of Justice countered that the Foreign Intelligence Surveillance Act had authorized Upstream’s review of communications between Americans and foreign “targets.”

In October 2015, U.S. District Judge T.S. Ellis III in Baltimore dismissed the lawsuit, finding a lack of evidence that the NSA, headquartered in Maryland, was conducting surveillance “at full throttle.”

Writing for the appeals court panel, however, Circuit Judge Albert Diaz found “nothing speculative” about the Wikimedia Foundation’s claims.

Diaz said the NSA interception and copying of communications showed “an invasion of a legally protected interest - the Fourth Amendment right to be free from unreasonable searches and seizures.”

The foundation could also pursue its First Amendment claim because it had “self-censored” some communications in response to the Upstream surveillance, Diaz said.

By a 2-1 vote, the same panel also ruled the plaintiffs lacked standing to challenge the NSA’s alleged “dragnet” to intercept “substantially all” text-based communications to and from the United States while conducting Upstream surveillance.

Justice Department spokesman Mark Abueg declined to comment.

Patrick Toomey, an American Civil Liberties Union lawyer representing the plaintiffs, said the ruling means Upstream “will finally face badly needed scrutiny” in the courts.

“This is an important victory for the rule of law,” he said in a statement. “Our government shouldn’t be searching the private communications of innocent people in bulk.”

Some Democratic and Republican lawmakers are working on legislation to curtail parts of Upstream. A section of FISA that authorizes the program expires at year end.

The case is Wikimedia Foundation et al v National Security Agency et al, 4th U.S. Circuit Court of Appeals, No. 15-2560.