What are the origins and effects of legal ambiguity in authoritarian regimes? Using a detailed case study of nationality rights in Jordan – which draws from interviews with 210 Jordanian political officials, judges, lawyers, activists, and citizens/residents – we develop a framework for understanding how legal ambiguity emerges, and how it matters, under authoritarianism. We first conceptualize four discrete forms in which legal ambiguity manifests: lexical ambiguity (in legal texts); substantive ambiguity (in status as law); conflictual ambiguity (between contradictory legal rules); and operational ambiguity (in enforcement processes). We then scrutinize the emergence and effects of legal ambiguity in Jordanian nationality policy by integrating historical process tracing, detailed interview evidence, and a content analysis of archival documents, laws, and court verdicts pertaining to nationality rights. Our findings contribute to scholarship on legal ambiguity, authoritarian legality, and discretionary state authority by showing that (1) crisis junctures make the emergence of legal ambiguity more likely; (2) legal ambiguity takes a variety of different forms that warrant conceptual disaggregation; and (3) different forms of legal ambiguity often have disparate effects on how authoritarian state power is organized and experienced in public life.