Briefing notes obtained under the Access to Information Act say the directive to the Ottawa-based Communications Security Establishment was one of seven such ministerial instructions issued in November 2011.
Details of the directive on assistance to police and other federal security agencies remain secret.
Recent allegations that a key CSE ally, the U.S. National Security Agency, has access to a wide sweep of Internet traffic has sparked questions and concerns about Canadian surveillance operations.
The CSE monitors foreign computer, satellite, radio and telephone traffic to zero in on threats to Canada and gather intelligence. It is not supposed to direct its activities at Canadians.
However, the agency — which employs computer experts, linguists and mathematicians — can provide assistance to the Mounties and CSIS, Canada's domestic spy service.
For instance, the CSE says it may assist with the decryption of emails or other files that these organizations have collected. It can also provide advice, training and equipment.
The briefing notes say the November 2011 ministerial directive on assistance was intended to replace one from 2001, drafted before post-9-11 legislation that expanded the CSE's mandate.
Of the other six directives approved by MacKay that month, one deals with the CSE's sharing relationships as a member of the Five Eyes intelligence community — Canada, the United States, Britain, Australia and New Zealand.
Another directive updates instructions on the collection of metadata — information associated with, but not the content of, telephone calls or emails. It could include time of the communication and location of the participants.
Opposition MPs have been asking MacKay pointed questions about the metadata directive, particularly in light of U.S. revelations about the NSA's telephone metadata collection program.
Four other MacKay directives are completely secret, though the notes say they are related to an unspecified "ministerial authorization" — permission granted by the defence minister to collect information that may risk incidental interception of the private communication of Canadians.
The briefing notes say MacKay issued eight such ministerial authorizations in November 2011, along with the seven overarching directives.
Details in the notes are sketchy, but six of these authorizations were related to the gathering of foreign intelligence, while two were related to the CSE's role in protecting Canadian government computer systems.
One of the intelligence gathering authorizations involved "interception activities" in support of Canada's mission in Afghanistan. It has long been known that the CSE has used its technical expertise to assist in the fight against the Taliban.
The defence minister is allowed to issue such authorizations only if the interception is directed at foreigners outside Canada, the information could not be obtained through other means, the expected intelligence value is high, and measures are in place to protect the privacy of Canadians.
CSE watchdog Robert Decary outlined in a lengthy statement Thursday the steps he takes to ensure the spy agency follows the law. Decary said his employees have "unobstructed access" to CSE systems, observe CSE analysts first-hand to see how they do their work, interview them, and test information obtained against the contents of the CSE's databases.
"I am completely independent and operate at arm's length from the government," Decary wrote.
Decary said that when other agencies request assistance from the CSE, he verifies that the eavesdropping agency complies with any court-ordered limitations — such as conditions in a judge's warrant — on the organization seeking help.
He added that he had reviewed the CSE's metadata activities and "have found them to be in compliance with the law and to be subject to comprehensive and satisfactory measures to protect the privacy of Canadians."
However, Decary said he had already approved — prior to recent events — a specific review relating to the CSE's metadata collection and use.
In a letter Thursday, NDP digital issues critic Charmaine Borg asked House Speaker Andrew Scheer for an emergency debate on how Canadians' personal information is being collected by national security and law enforcement agencies.
Borg also called for appropriate parliamentary supervision and reporting of any disclosures to police by the CSE.
"As parliamentarians, it is our responsibility to balance public safety and national security interests against the privacy rights of law-abiding Canadians," Borg said in a statement.
Canadians have a right to know how much clandestine surveillance is being carried out on the Canadian public, said Green Party Leader Elizabeth May.
"We first heard about the prevalence of spying on private citizens last week in the U.S., but it is obvious that both countries share communication infrastructure and have passed similar security-related laws," she said.
"It’s time citizens were given more information regarding the kind of spying being carried out, how, and why."
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