“26. … The effect of the United States Supreme Court’s holdings is that the conditions under which Mr. Khadr was held and was liable for prosecution were illegal under both U.S. and international law at the time Canadian officials interviewed Mr. Khadr and gave the information to U.S. authorities. Hence no question of deference to foreign law arises. The Charter bound Canada to the extent that the conduct of Canadian officials involved it in a process that violated Canada’s international obligations.”
Section 7 of the Charter provides:
“Everyone has the right to life, liberty and security of the person and the right not to be deprived thereof except in accordance with the principles of fundamental justice.”
Here, fundamental justice required that Mr Khadr be given, to facilitate his defence to charges that were to be tried at Guantanamo Bay, copies of certain interviews. This was analogous to, but not the same as, the disclosure obligation that would arise in a domestic prosecution. The difference here is that the Canadian authorities were not prosecutors:
“32. … The scope of the disclosure obligation in this context is defined by the nature of Canada’s participation in the foreign process. The crux of that participation was providing information to U.S. authorities in relation to a process which is contrary to Canada’s international human rights obligations. Thus, the scope of the disclosure obligation must be related to the information provided to U.S. authorities.”
The extent of this disclosure requirement was to be determined in accordance with s 38.06 of the Canada Evidence Act, which involves a judicial oversight procedure to protect security and public policy considerations.
It is clear that even if the US SC had held the Guantanamo Bay procedures to be legitimate, the SCC would not have been obliged to agree: para 25.
This case distinguished the facts of R. v. Hape, 2007 SCC 26 (CanLII),  2 S.C.R. 292, 2007 SCC 26 (blogged here 11 June 2007), and applied dicta in that case on the limits of comity:
“ 18. … comity cannot be used to justify Canadian participation in activities of a foreign state or its agents that are contrary to Canada’s international obligations. It was held that the deference required by the principle of comity “ends where clear violations of international law and fundamental human rights begin” (Hape, at paras. 51, 52 and 101, per LeBel J.). The Court further held that in interpreting the scope and application of the Charter, the courts should seek to ensure compliance with Canada’s binding obligations under international law (para. 56, per LeBel J.).”
On the question of the material that should be disclosed here, while that was left to the designated judge to determine, the SCC observed that confining it to the interviews that had been given to the US authorities may not be sufficient for the conduct of Mr Khadr’s defence:
“34. … disclosure of an inculpatory statement shared with the U.S. authorities might require disclosure of an exculpatory statement not shared to permit Mr. Khadr to know his jeopardy and prepare his defence. It would seem to follow that fairness requires disclosure of all records in any form of the interviews themselves — whether or not passed on to U.S. authorities — including any transcripts, recordings or summaries in Canada’s possession. For similar reasons, it would seem to follow that Mr. Khadr is entitled to disclosure of information given to U.S. authorities as a direct consequence of Canada’s having interviewed him.”
[Update: the Court does not have jurisdiction to compel the government to order Mr Khadr's return to Canada: Canada (Prime Minister) v Khadr  SCC 3 (29 January 2010).]