The suit filed in federal court in Maryland accuses the NSA of scooping up virtually everything sent via the Internet between Americans and people outside the United States, and then scouring it to identify and monitor foreign intelligence targets.
A similar challenge was turned away by the U.S. Supreme Court, which said the plaintiffs couldn't prove they'd been harmed. This lawsuit says that's changed since the government confirmed the surveillance after its scope and details were leaked by former government contractor Edward Snowden in 2013.
This "upstream" surveillance of the Internet's "backbone" of digital networks reaches far beyond any individuals the government is targeting to combat terror attacks, and violates constitutional protections of free speech and privacy, the plaintiffs say.
ACLU staff attorney Patrick Toomey said Tuesday that Snowden's leaks changed the whole legal paradigm.
"We believe the Snowden disclosures will make an immense difference in how this case will play out," Toomey said. "Prior to Snowden, the public had never heard of upstream surveillance. But based on those disclosures and what the government has acknowledged itself, we know the government isn't just surveilling its targets, its surveilling everyone."