Snowden, who appeared via video link at Toronto's Roy Thomson Hall during a semi-annual Munk debate that state surveillance today is a euphemism for mass surveillance.
"It's no longer based on the traditional practice of targeted taps based on some individual suspicion of wrongdoing," Snowden said in the brief video. "It covers phone calls, emails, texts, search history, what you buy, who your friends are, where you go, who you love."
The video was screened as two of the debaters — former U.S. National Security Administration director General Michael Hayden and well-known civil liberties lawyer and Harvard law professor Alan M. Dershowitz — argued in favor of the debate statement: "Be it resolved state surveillance is a legitimate defense of our freedoms."
In opposition were Glenn Greenwald, the journalist whose work based on the Snowden leaks won a Pulitzer Prize last month, and Alexis Ohanian, the co-founder of social media website reddit.
The Snowden documents, first leaked last June, revealed that the U.S. government has programs in place to spy on hundreds of millions of people's emails, social networking posts, online chat histories, browsing histories, phone records, phone calls and texts. "Nearly everything a typical user does on the Internet," in the words of one leaked document.
Greenwald opened the debate by condemning the NSA's own slogan, which he said appears repeatedly throughout its own documents: Collect it all.
"What is state surveillance? If it were about targeting in a discriminate way against those causing harm, there would be no debate," said Greenwald. "The actual system of state surveillance has almost nothing to do with that. What state surveillance actually is, is defended by the NSA's actual words, that phrase they use over and over again, 'collect it all.'"
Hayden and Dershowitz spent the rest of the hour and a half or so denying that the pervasive surveillance described by Snowden and Greenwald even exists and that the ongoing surveillance programs are necessary to prevent terrorism.
"Collect it all doesn't mean collect it all!" said Hayden, drawing laughs from the audience.
Greenwald went on to spar with Hayden and Dershowitz over whether the current method of metadata collection would have prevented the terrorist attacks on Sept. 11, 2001.
While Hayden argued that intelligence analysts would have noticed the number of calls from San Diego to the Middle East and caught the terrorists who were living inside the US illegally, Greenwald argued that one of the primary reasons US authorities failed to stop attacks is because they were taking in too much information to accurately sort through it all.
Before the debates began, the audience voted 33 in favor of the statement, "Be it resolved state surveillance is a legitimate defence of our freedoms," while 46 percent voted against. The debate ended with 59 percent of the audience siding with Greenwald and Ohanian.
The Munk Debates are a Canadian charitable initiative established by co-founders Melanie and Peter Munk, chairman and founder of the mining company Barrick Gold.
AP from TORONTO