The three men were accused of having links to radical Islamist groups
A Canadian inquiry has concluded that officials there contributed indirectly to the torture of three Canadian citizens in Syria.
The men were arrested in Syria on suspicion of involvement in terrorist activities, but were released in 2004.
Returning to Canada, they said they were tortured and that Canada supplied Syria with questions to ask them.
However, the judge said the officials concerned seemed to have believed they were acting in Canada's best interests.
Ahmad El Maati, Abdullah Almalki and Muayyed Nureddin, all of Middle Eastern origin, were separately arrested by Syrian military intelligence between 2001 and 2004.
They were accused of having links to radical Islamist groups but have denied any such connection.
Judge Frank Iacobucci, who headed the closed-door, government-initiated inquiry in Ottawa, concluded that the men had, as they claimed, been subjected to abuse which "amounted to torture" in Syria.
He said torture was "a pernicious practice that is just beyond any kind of defence" and that their mistreatment had "resulted indirectly" from the actions of the Canadian intelligence agencies and officials.
These actions included the sharing of information on the men, the sending of questions to be put to them by Syria and, in some cases, a failure to provide effective consular services.
But Mr Iacobucci said he had found no evidence that any of the officials involved were "seeking to do anything other than carry out conscientiously the duties and responsibilities of the institutions of which they were a part".
The inquiry followed the case of torture victim Maher Arar
"You're looking at this protection of the state against terrorist threats, and you've got to take that very seriously," he said.
He said it was "neither necessary nor appropriate" for him to rule on the role of any individual official.
The judge also made clear that nothing in his report should be taken as an indication of there being truth in the allegations against the men, as the investigation had no mandate to explore this.
He said he hoped Canada would "continue to strive to get the balance, the equilibrium, between the protection of national security interest along with the protection, preservation and enhancement of freedoms".
The investigation was ordered in the wake of the case of Maher Arar, a Syrian-born Canadian who was deported to Syria in 2002 and tortured.
Canada compensated him after exonerating him and finding that the US had acted on Canadian information.