Federal Court of Canada Judge Richard Mosley has slammed the Canadian Security Intelligence Service (CSIS) for its “deliberate decision to keep the court in the dark” when the spy agency applied for warrants, issued in 2009, permitting it and the Communication Security Establishment Canada (CSE) to intercept the electronic communications of some Canadians abroad from within Canada.

In redacted documents released in December, Mosley wrote that, “It is clear that the exercise of the court's warrant issuing has been used as protective cover for activities that it has not authorized.”

Those activities included using foreign intelligence agencies to intercept Canadians' electronic messages, a violation of the Federal Court's authority.

Midway through 2013, Mosley discovered that CSE had enlisted assistance from one or more of Canada's allies within the so-called Five Eyes intelligence-gathering alliance, and he summoned representatives of CSIS, CSE and the government to answer for their actions. After hearing their explanations, he concluded: “This was a breach of duty of candour owed by [CSIS] and their legal advisors to the court.” He wrote that CSIS understood the law but deliberately misinterpreted it.