The American Civil Liberties Union filed a lawsuit against the Obama administration on Tuesday over the National Security Agency's ongoing data collection.
The ACLU's suit asks the NSA to stop monitoring millions of Americans' phone call logs and other communications records, and demands that the currently held records be purged, the New York Times reported.
The NSA's top-secret surveillance program — involving nine major US telecommunications companies and code-named PRISM — was revealed last week by the agency's 29-year-old former employee Edward Snowden.
The ACLU contended in its complaint that PRISM "gives the government a comprehensive record of our associations and public movements, revealing a wealth of detail about our familial, political, professional, religious and intimate associations," and that it "is likely to have a chilling effect on whistle-blowers and others who would otherwise contact" the organization for help.
"This dragnet program is surely one of the largest surveillance efforts ever launched by a democratic government against its own citizens," said Jameel Jaffer, ACLU deputy legal director, in a statement.
"It is the equivalent of requiring every American to file a daily report with the government of every location they visited, every person they talked to on the phone, the time of each call, and the length of every conversation," he added.
Though the civil liberties advocacy organization has filed similar suits in the past, the Justice Department has usually been able to have the cases thrown out by either claiming that the plaintiffs could not prove they were personally affected, or arguing that state secrets would be compromised, according to the Times.
However, the ACLU is a customer of Verizon Communications, the first company to be outed as part of the NSA's data collection, which gives them direct standing to file a suit against the US government.
The Justice Department declined to comment on the lawsuit.
The ACLU announcement comes as Google, one of the companies involved in the NSA's PRISM program, requested the right to make public the amount of national security requests it receives as well as their scope.
"Google’s numbers would clearly show that our compliance with these requests falls far short of the claims being made. Google has nothing to hide," wrote Google's Chief Legal Officer David Drummond in an open letter to Attorney General Eric Holder and FBI Director Robert Mueller.
"Transparency here will... serve the public interest without harming national security," Drummond added.
Officials have not yet responded to Google's request.
The ACLU suit, filed in New York, also comes just a day after it partnered with Yale Law School's Media Freedom and Information Access Clinic to file a motion to force the Foreign Intelligence Surveillance Act court to disclose its justification for allowing the NSA's intelligence gathering to go forward.
"There needs to be a bright line on where intelligence gathering stops," said New York Civil Liberties Union executive director Donna Lieberman. "If we don't say this is too far, when is too far?"