Mass surveillance schemes like PRISM and Tempora run by National Security Agency (NSA) and Government Communications Headquarters (GCHQ) are utterly ineffective, according to the man who revealed the projects, Edward Snowden.
Snowden made the claim over a video feed at a Council of Europe Parliamentary Assembly on improving the protection of whistleblowers.
"The mass-surveillance campaigns have never been shown to be effective. The bulk surveillance programmes never stopped a single incident, not one," he said.
Snowden said the agencies would be better placed pursuing criminals and terrorists with co-ordinated, targeted surveillance campaigns.
"The top spy in the US – the director of National Intelligence James Clapper – stated in a private meeting that was later reported in the press, that regardless of their fears, terrorists and criminals have to communicate. And when they do, they will always make mistakes and give us ways to find them," he said.
"For example, we've all known about telephone wire taps for years now, but criminals still use them. We know about internet surveillance, but we still use email because it's critical to our lives. We have ways to monitor them."
Snowden rose to infamy in 2013 when he leaked classified documents to the press proving that the NSA is siphoning vast amounts of data from numerous technology companies, including Facebook, Microsoft, Google and Yahoo as a part of a co-ordinated mass-surveillance campaign, codenamed PRISM.
Snowden said the PRISM campaign, and others that have come to light, proved the clout wielded by groups such as the NSA and GCHQ meant tactics to gather data were always going to be developed, regardless of legal frameworks.
"The NSA and other intelligence services never rely on a single method to gather information. They don't have an exhaustible, finite supply of intelligence-gathering systems,” he said.
"Intelligence agencies are like a factory, whenever they need a new method they make one; they get scientists and researchers and get a new one. If a government or someone burned a specific method they'd just make more. That's how any intelligence agency around the world runs."
Snowden's participation at the Council of Europe's Parliamentary Assembly is one of a select few public appearances since the US blocked his passport and travel rights, leaving him stranded in Russia.
Snowden urged technology professionals to develop more user-friendly security and anonymising services to help protect the public from government surveillance programs such as PRISM, while speaking through a video feed in a privacy discussion at the SXSW conference in March.
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