US civil liberties groups including American Civil Liberties Union (ACLU) and Yale University’s Media Freedom and Information Access Clinic have sued the US government over details regarding the National Security Agency (NSA) overseas snooping activities.

Being sued in the wake of a New York District Judge William Pauley’s ruling that a separate NSA spying programme was legal, the latest suit is mainly aimed at seeking information about the ‘vast quantities’ of information that the agency had been allegedly gathering.

ACLU National Security Project staff attorney Alex Abdo said that although EO 12,333 permits the government to target foreigners abroad for surveillance, recent revelations have confirmed that the government interprets that authority to permit sweeping monitoring of Americans’ international communications.

"How the government conducts this surveillance, and whether it appropriately accommodates the constitutional rights of American citizens and residents whose communications are intercepted in the course of that surveillance, are matters of great public significance and concern," Abdo said.

"While the government has released several documents describing the rules that govern its collection and use of Americans’ international communications under statutory authorities regulating surveillance on U.S. soil, little information is publicly available regarding the rules that apply to surveillance of Americans’ international calls and emails under EO 12,333.

"For instance, recent news reports indicate that, relying on the executive order, the NSA is collecting: nearly 5 billion records per day on the location of cell phones, including Americans’ cell phones; hundreds of millions of contact lists or address books from personal email and instant messaging accounts; and information from Google and Yahoo user accounts as that information travels between those companies’ data centres located abroad."

In addition, privacy campaigners have also released details of the NSA’s access to phones and networking hardware.

We now know too well that unchecked surveillance authority can lead to dangerous overreach.

"That’s why we are fighting for the release of documents that would shed light on the internal rules that the executive has set for itself when it monitors international communications abroad — including Americans’ international communications."