An independent US government privacy board has ruled the National Security Agency's (NSA) surveillance through mass collection of citizens' web and phone data is illegal and should be shut down.
The recommendation by the Privacy and Civil Liberties Oversight Board came in a 238-page report that states the surveillance scheme violates restrictions about civil liberties in the Patriot Act.
"This program should be ended, allowing for a transition period," said James Dempsey, a member of the five-man board on the release of the report.
The board came to the conclusion that the mass collection of data acquired through snooping on communications has had little to no effect in the fight against terrorism.
"We have not identified a single instance involving a threat to the United States in which the telephone records program made a concrete difference in the outcome of a counterterrorism investigation," said the report.
"Moreover, we are aware of no instance in which the program directly contributed to the discovery of a previously unknown terrorist plot or the disruption of a terrorist attack."
The extent of mass surveillance by the authorities was leaked by former US government IT contractor Edward Snowden, who is currently living in exile in Russia.
Snowden has been denounced as a traitor and a spy by a number of high profile US figures, but attorney general Eric Holder has hinted that the whistle-blower might be able to return to the United States under some sort of deal. However, he also suggested a full pardon was out of the question.
"We've always indicated that the notion of clemency isn't something that we were willing to consider. Instead, were he coming back to the US to enter a plea, we would engage with his lawyers," Holder told NBC News.
Snowden took place in a live webchat at around the same time as the news report but gave no indications as to whether he'd enter a plea bargain due to a "failure" surrounding whistle-blower related legislation in his home country.
"Returning to the US, I think, is the best resolution for the government, the public, and myself, but it's unfortunately not possible in the face of current whistle-blower protection laws, which through a failure in law did not cover national security contractors like myself." he said.
Snowden also argued that he had no other option when it came to revealing the mass surveillance by governments as there weren't any channels in place for him to raise concerns with independent bodies.
"If we had ... a real process in place, and reports of wrongdoing could be taken to real, independent arbiters rather than captured officials, I might not have had to sacrifice so much to do what at this point even the president seems to agree needed to be done," he said.