The most powerful U.S. spymaster of the post-9/11 era envied his Canadian counterparts for a singular advantage they held on him – their ability to push through secret surveillance programs without generating any pushback from politicians or judges.

"Being much smaller, [Communications Security Establishment Canada] had a lot of agility … it got changes in its law ahead of when the United States was able to make that happen," said Michael Hayden, a retired four-star general. "You were able to get it through your Parliament in an efficient way."

Speaking in an exclusive interview with The Globe and Mail, the controversial intelligence chief who served under President George W. Bush, said that the U.S. National Security Agency and CSEC use similar electronic-eavesdropping techniques to collect foreign intelligence, as do other allies.

Story continues below advertisement

But, he complained, the NSA is "held up as a renegade" even though its operations are blessed by the president and scrutinized by other branches of the U.S. government.

The NSA gets "more oversight than any other service," Gen. Hayden said. "Many things that an American has to go to a court for, the British, Canadian, Australian and New Zealand services all have completed within the executive – through ministerial warrants."

On Friday, Gen. Hayden will be in Toronto singing the praises of U.S. intelligence oversight as he faces off in the annual Munk Debates against American journalist Glenn Greenwald.

The two antagonists in this much anticipated contest have never met before, yet they are bound together by Edward Snowden, the former NSA contractor who last year leaked a massive trove of secret information.

The details centre on surveillance programs that Gen. Hayden pioneered in secrecy, but which were leaked to Mr. Greenwald and a handful of other trusted journalists to publicize globally.

Gen. Hayden argues the leaks have been extraordinarily damaging. A football fanatic who was never enthralled with oversight as a serving spymaster, he presided over many highly contentious security programs of unprecedented reach. He did this first as NSA boss, collecting Americans' telecommunications data on a massive scale, and later as Central Intelligence Agency chief, stepping up Predator drone campaigns targeting foreign terrorism suspects

Mr. Hayden would not speak to Canadian intelligence programs that he was privy to. In Canada, ministerial directives and authorizations governing surveillance practises are considered classified.

Story continues below advertisement

Last year, The Globe and Mail published redacted versions of "metadata" ministerial directives – orders signed by Canadian defence ministers dating back a decade under both Liberal and Conservative governments, and showing that Ottawa has been intercepting some citizens' telecommunications trails despite the usual proscriptions banning domestic spying.

Parliamentarians never raised questions about such surveillance because they did not know about it. Unlike the United States, where "warrantless wiretapping" created a public controversy in the Bush era, Canada has no "select committees" of politicians who are afforded glimpses of secret surveillance practises. Nor are there intelligence courts where sitting judges can challenge surveillance programs before they take root.

Three months after the Sept. 11, 2001 attacks, Parliament passed the omnibus Anti-Terrorism Act. Certain clauses empowered CSEC to collect some forms of domestic communications data – yet these clauses received no attention from MPs.

Gen. Hayden said relations between the NSA and CSEC are so cozy he would "routinely" play host to chiefs of the Canadian agency at his home. The Snowden leaks have shown the agencies are constantly sharing techniques and refining them.

The leaks have spawned a global debate about whether Washington, Ottawa and other English-speaking allies have been overzealously spying on foreign allies, their own citizens and technology corporations.

Gen. Hayden contends the NSA has always faced constraints.

Story continues below advertisement

"People say 'you were lawless,'" he said. "But we drew lines."