The Presumption Against Interference with Vested Rights: Creating Structure out of the Confusion

Canadian courts interpret statutes flexibly, as they remain unbridled by strict interpretive rules or principles. Consequently, ambiguity in statutory interpretation has emerged, particularly regarding the temporal application of statutory amendments. In this article, the author suggests that clearer rules should be established to remedy such uncertainty, focusing predominantly on clarifying the presumption against interference with vested rights. The article first proposes a step-by-step approach to the vested rights analysis, explaining how it operates and interacts with other temporal application presumptions. Next, the article traces the history and jurisprudence of the presumption against interference with vested rights, and attempts to resolve outstanding issues relating to the presumption. Finally, it applies this background to the proposed step-by-step approach, ultimately synthesizing the law and theory underpinning the discussed presumptions.