This article examines three factors that were influential in the Supreme Court’s 2021 decision in Canada v. Alta Energy Luxembourg SARL with respect to the potential application of the general anti-avoidance rule to the Canada-Luxembourg tax treaty: (1) the presumption that the contracting states know about each other’s domestic income tax system, (2) the dual nature of tax treaties as statutes and treaties, and (3) the theory of economic allegiance. It argues that, irrespective of whether one considers the court’s decision to be correct or incorrect, the court did not understand or apply these factors properly.