One of the challenges brought by the appellant to the Canadian FATCA legislation (i.e., the Canada-United States Enhanced Tax Information Exchange Agreement Implementation Act and ss. 263 to 269 of the Income Tax Act) was that "to the extent that Canada's disclosure of account holder information to the US constitutes 'assistance in collection,' Canada is prohibited [by Art. XXVI A of the Canada-U.S. Convention] from disclosing such information as it relates to Canadian citizens…[so that] account holder information should not be disclosed in cases in which the taxpayer was a Canadian citizen at the time the revenue claim arose" (para. 58). In rejecting this submission and before dismissing the motion, Martineau J stated (at para. 72):
Article XXVI A applies only to cases in which tax liability has been determined and is enforceable, and does not apply to the assessment of tax payable, the verification of taxpayer compliance, or related exchanges of information.
See summary under Treaties – Art. 27.