The disclosure that the U.S government secretly collects data from telephone and internet services has raised concerns by some privacy advocates over Canada's own surveillance techniques and what kind of information Ottawa is mining from Canadians.

"The problem is we just don't know. So much of this is shrouded in secrecy," said Michael Geist, a University of Ottawa law professor and Canada Research Chair in Internet and E-commerce Law. "The argument is 'we can't tell you because that will have an impact on our security operations,' yet we do live in a democratic society. Sometimes there has to be somebody watching the watchers."

Recent media reports have revealed the existence of U.S. National Security Agency surveillance programs that gather hundreds of millions of U.S. phone records while searching for possible links to terrorist targets abroad. The programs have also allowed the government to tap into nine U.S. internet companies to gather usage data to detect suspicious behaviour that begins overseas.

These surveillance operations do not look into the actual content of such communications but instead collect "metadata" — or information about the data itself. So while a government official wouldn't have legal access to an actual phone call, they would have access to information about the call, which could include its time, location, the number called, and its duration.

Canada has its own eavesdropping agency, the Communications Security Establishment Canada (CSEC), which is charged with monitoring foreign communications. The agency clearly states that it "does not direct its activities at Canadians, Canadians abroad or any persons in Canada" and that it is prohibited by law from doing so.

But when it comes to looking into metadata information, CSEC may have more leeway. The Globe and Mail recently obtained documents under the Access to Information Act that reveal Defence Minister Peter MacKay in 2011 renewed a secret metadata eavesdropping program that had been secretly approved in 2005 by then Liberal Defence Minister Bill Graham.

The documents seem to be the first confirmation that the Canadian government is also engaged in metadata mining. They also suggest that Ottawa believes spying on metadata does not contravene any laws because it's "information associated with a communication" but not the communication itself.

Q&A: Why is the U.S. collecting phone data on its citizens?

A document, obtained by The Canadian Press, says the CSEC's use of metadata "will be subject to strict conditions to protect the privacy of Canadians, consistent with these standards governing CSEC's other programs."

It lists five steps the CSEC must take to protect Canadian privacy, though the steps themselves were deleted from the version released under the access law. Meanwhile, the federal privacy watchdog has said she will look into any implications for Canada posed by possible U.S. government snooping on a wide scale.

'Massive surveillance infrastructure'

"If this is as it appears to be, we're talking about a massive surveillance infrastructure," Geist said. "The very kind of surveillance we decry in other countries appears to be occurring in ours where seemingly all telephone calls are monitored that can tell quite a story. Indeed there have been some experts who have said the metadata can ultimately tell more than the content of the calls themselves."

Geist dismissed the argument that those who are not doing anything wrong should have nothing to worry.

"We're talking about tracking of every kind of information. The people you talk to, the kinds of things you're interested in," he said. "It's entirely possible that people find themselves caught up in things that are completely innocuous."

Many people generally underestimate the "revealing potential" of metadata, added Tamir Israel, staff lawyer with the Samuelson-Glushko Canadian Internet Policy & Public Interest Clinic at the University of Ottawa.

He said extremely sophisticated analytical tools are applied to metadata, which can be a rich source of information.

"There is a broader concern, which I think Canadians should really be concerned about, and that is the democratic harm. Just allowing these types of unfettered access actually harms our democratic system in very tangible ways," Israel said.

The actual metadata CSEC investigates, whether it be telephone records or email transactions, is not clear, as that information had been blacked out from the documents, said Bill Robinson, a researcher who blogs about CSEC.

Revelations not surprising

The revelations about CSEC's metadata collection weren't surprising, he said, but they raise more questions about the nature of the metadata being collected and how the data is being processed.

"We don't know exactly the degree of metadata they're collecting. It could be like NSA, which is the whole country's records," he said.

Meanwhile, during question period on Monday, MacKay did not comment on the 2011 renewal of the metadata eavesdropping program, saying only that the eavesdropping service was operating within the law.

"This program is specifically prohibited from looking at the information of Canadians," MacKay said. "This program is very much directed at activities outside the country, foreign threats, in fact. There is rigorous oversight. There is legislation in place that specifically dictates what can and cannot be examined."

The CSE is overseen by Robert Décary, a retired judge who has acted as the CSE's commissioner since 2010. His office says he continues efforts begun in 2006 by a predecessor to monitor the collection of metadata.

But Israel said Canadians should still be concerned about the secrecy of the program and "the fact that these orders are being interpreted in secret and have never actually seen any public debate or legal challenge."

"Nobody can legally challenge how CSEC is interpreting their powers."

The office of privacy commissioner Jennifer Stoddart has said the scope of information reportedly being collected raises significant concerns.

Stoddart said while it is difficult to assess the merit of the allegations, she will confer with Décary to determine how the personal information of Canadians may be affected.