Normative literature on the Catalan crisis is largely occupied with the conflict’s central legalistic problem: can political units like Catalonia be allowed to split off from Spain unilaterally? This article reframes the issue and asks why secessionist Catalans should ever abide by Spanish legal constraints, given that Spanish law is precisely the institution they are politically trying to get rid of. It focuses on the anti-secessionist role played by the Spanish Constitutional Court between 2010 and 2017 and studies three arguments (...) why Catalans supposedly have to accept the Court’s authority. The article contends that two arguments—the “mutual benefit argument” and the “law and democracy” argument—will not be independently persuasive to Catalan secessionists. Instead, the Constitutional Court’s authority must ultimately be grounded in a different type of argument: the “law and order argument.” Secessionist Catalans’ supposed duty to obey the orders of the Constitutional Court is ultimately not rooted in a positive service provided by the Court, but in the disruptive effects of disobeying. That exposes an explanatory defect in Joseph Raz’s influential theory of authority, which seeks to ground authority exercises in a concept in prior reason or their capacity to make our life better. That conceptualization misses the key decisionistic element to political authority: its capacity to constitute our reasons, that is, to define the terms that give meaning to our evaluations. (shrink)