"I will be shocked if the events of this week don't result in far greater secrecy powers and far greater surveillance powers than existed previously," Glenn Greenwald told The Canadian Press on Thursday.
"I've seen it so many times where the fear and nationalism that get generated by these events render almost inevitable not just the enactment of legislation that was already pending but I'll bet new and wholly more extreme measures as well."
Greenwald, a journalist and author, chronicled Edward Snowden's revelations of extensive National Security Agency surveillance programs last year.
Shortly after Greenwald's comments, Prime Minister Stephen Harper told the Commons the "surveillance, detention and arrest" powers of the Canadian Security Intelligence Service will quickly be toughened.
"They need to be much strengthened, and I assure you, Mr. Speaker, that work — which is already underway — will be expedited," he said.
Greenwald was in Montreal to deliver a lecture at McGill University as part of a swing through several Canadian cities.
While working at the Guardian newspaper in Britain, Greenwald put the spotlight on a treasure trove of data from top-secret documents leaked by Snowden, a former National Security Agency contractor and whistleblower.
Greenwald has since become co-editor of The Intercept, which looks at security issues.
He said Canada should not be underestimated when it comes to intelligence gathering, noting it is part of the so-called "Five Eyes" alliance of countries that includes the United States, the United Kingdom, Australia and New Zealand.
"They literally want to collect and store every electronic communication activity that takes place by and between human beings everywhere in the world, which is another way of saying they want to eliminate privacy in the digital age," he said.
"Canada is a recipient of enormous amounts of information that come from this alliance and they are contributors of enormous amounts of information that come from this alliance."
Greenwald questioned government arguments that increased surveillance has thwarted terrorist plans, saying the avalanche of information collected may have even hindered efforts.
He said intelligence activity didn't prevent this week's killing of Canadian soldiers in Quebec and Ottawa, while the significant capabilities of the National Security Agency didn't stop the Boston Marathon bombing last year or an attempted attack on New York's Times Square in 2010.
"Once you allow a government to engage in massive surveillance, rather than targeted surveillance, they end up collecting so much information, so much data that it's impossible for them to know what it is they have," he said.
"It actually subverts the goal of counter-terrorism."
He said Canadians still have a greater risk of dying from slipping in the bathtub or getting hit by lightning than from a terrorist attack.
Greenwald acknowledged there could be some pressure from the United States for Canada to toughen its laws.
He also said Canadians have to realize that their foreign policy, such as the decision to help fight ISIL in Iraq, has consequences despite the country's peaceful reputation.
"When you have your military in other countries, if you're sending fighter jets to drop bombs on countries, that's not peaceful."
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