Canada's spy agency relied so heavily on information gleaned from torture that is ability to protect Canadians would be harmed if it weren't allowed to do so, a letter from a CSIS head indicated.

The letter, obtained by the Montreal Gazette, was sent from then- CSIS Director Jim Judd to then-Public Safety Minister Stockwell Day, in January of 2008, as the government was preparing new legislation on national security certificates (NSLs).

Judd warned that an amendment to the new law, which would prevent the use of torture to issue NSLs, could "render unsustainable the current security certificate proceedings."

NSLs allow Canadian authorities to detain non-citizens indefinitely without trial, where evidence exists that they are a national security risk. A cabinet minister must sign off on any use of an NSL.

If the NSL amendment were interpreted to mean that Canada could not rely on evidence initially obtained from governments that may have tortured, and then independently corroborated, "the Government's ability to act in the interest of public safety on threat-related information or advice provided by CSIS could be significantly and negatively affected," the letter stated,

CSIS memo shows Canada's reliance on torture

The letter "suggests a disturbing acceptance by the national security agency of torture as a legitimate strategy to counter terrorism," the Gazette's Catherine Solyom reports.

The letter does not suggest that Canada has engaged in torture.

However, it does come in the wake of years of allegations that Canada has looked the other way as Afghan authorities tortured detainees handed over to them by Canadian soldiers.

In 2009, Canadian diplomatic Richard Colvin alleged ongoing torture in Afghan jails and Canadian authorities' "complicity" in the matter.

"According to our information, the likelihood is that all the Afghans we handed over were tortured", Colvin said in testimony to Parliament in November, 2009. "For interrogators in Kandahar, it was a standard operating procedure."

Colvin's claims appear to have been backed up recently by a UN report that found “a compelling pattern and practice of systematic torture and ill-treatment” in numerous prison facilities around the country.

Judd's letter to the public safety minister came two years before a diplomatic cable released by Wikileaks showed Judd to be contemptuous of Canadian courts' stance on torture.

Judd told U.S. State Department official Eliot Cohen that the courts were tying CSIS "in knots" and that they had an "Alice in Wonderland" worldview.