In its decision in Canada (Citizenship and Immigration) v Vavilov the Supreme Court of Canada fundamentally altered Canadian administrative law.     For the most part, the Court’s analysis was comprehensible and comprehensive.     But on a number of key issues, the implications of Vavilov are obscure. In order of importance, these unresolved issues are: how does Vavilov apply to internal statutory appeals, what framework governs procedural fairness in administrative law, is arbitration subject to administrative law principles, are administrative decisions touching the Charter of Rights and Freedoms still to be reviewed deferentially, and what are the constitutional foundations of Vavilovian judicial review?     In my Hugh Ketcheson QC Memorial Lecture, I will explain the importance of these issues and lay out answers and solutions which are faithful to the Vavilov framework.