New York - A US spying programme that collects data about millions of Americans' phone calls is illegal, a federal appeals court ruled on Thursday, adding pressure on lawmakers to decide quickly whether to end or replace the programme, which was intended to help fight terrorism.
While stopping short of declaring the programme unconstitutional, the 2nd US Circuit Court of Appeals in Manhattan said Congress did not authorise the National Security Agency to collect Americans' phone records in bulk.
The existence of the NSA's collection of "bulk telephony metadata" was first disclosed in 2013 by former NSA contractor Edward Snowden.
Writing for a three-judge panel, Circuit Judge Gerard Lynch said Section 215 of the Patriot Act governing the collection of records to fight terrorism did not authorise what he called the NSA's collection of a "staggering" amount of information, contrary to claims by the Bush and Obama administrations.
"Such expansive development of government repositories of formerly private records would be an unprecedented contraction of the privacy expectations of all Americans," Lynch wrote in a 97-page decision.
"We would expect such a momentous decision to be preceded by substantial debate, and expressed in unmistakable language. There is no evidence of such a debate."
Resistance
The appeals court did not issue an order to stop the collection of data, noting that parts of the Patriot Act including Section 215 will expire on June 1. Lynch said it is for Congress to make clear whether it considers the NSA programme permissible.
Federal appeals courts in Washington, DC and California are also considering whether the program is legal.
The US Department of Justice had called the programme necessary to protect national security.
Ned Price, a spokesperson for the White House's National Security Council, said US President Barack Obama has been clear he wants to end the existing NSA programme, and is encouraged by the "good progress" in Congress to find an alternative preserving its "essential capabilities".
The ACLU did not immediately respond to a request for comment.
Last week, the House Judiciary Committee voted 25-2 in favour of the USA Freedom Act, which would end the bulk collection of telephone data, and the bill is expected to pass the full House.
A similar bill has been proposed in the Senate, with backing from some liberal Democrats and conservative Republicans, but has faced resistance from senators including Majority Leader Mitch McConnell. Passage remains uncertain.
Senator Rand Paul, a Kentucky Republican and presidential candidate, tweeted after the decision that "phone records of law abiding citizens are none of the NSA's business! Pleased with the ruling this morning."
Another presidential candidate, Democratic Senator Bernie Sanders of Vermont, tweeted that "the NSA is out of control and operating in an unconstitutional manner".
Thursday's decision overturned a December 2013 dismissal of the ACLU's lawsuit by US District Judge William Pauley in Manhattan, who called the NSA programme a government "counter-punch" to terrorism at home and abroad.