The Canadian Senate has long been considered an institutional pariah, viewed as an undemocratic, outmoded warehouse for patronage appointments and mired in spending and workload scandals. After decades of debate about reform, in 2014 the federal government was compelled to refer constitutional questions to the Supreme Court relating to its attempts to enact senatorial elections and term limits. Constitutional Pariah explores the aftermath of Reference re Senate Reform. In its first significant attempt to articulate the boundaries between key procedures in the constitutional amending formula, the Court ruled out major unilateral alteration of the Senate by Parliament. Ironically, the decision resulted in one of the most sweeping parliamentary reforms in Canadian history, creating a pathway to informal changes in the appointments process that have curbed patronage and partisanship. Emmett Macfarlane situates this incisive analysis within the context of the roles of the upper house, its evolving performance, and historical efforts at reform. Despite reinvigorating the Senate, Reference re Senate Reform has far-reaching implications for constitutional reform in other contexts. Macfarlane’s sharp critique suggests that the Court’s nebulous approach to the amending formula raises the spectre of a frozen constitution, unable to evolve with the country.