Presuppositionisthesemantic-pragmaticphenomenon whereby a statement contains an implicit precondition that must be taken for granted (presupposed) for that statement to be felicitous. This article discusses the role of presupposition in legislative texts, using examples from Swiss constitutional and administrative law. It illustrates (a) how presuppositions are triggered in these texts and (b) what functions they come to serve, placing special emphasis on their constitutive power. It also demonstrates (c) how legislative drafters can distinguish between “good” presuppositions and “bad” presuppositions by weighing their main advantage, conciseness, against their main flaw, reduced transparency. The present study argues that, if employed carefully, presuppositions can be a useful stylistic means to keep legislative texts free from unnecessary clutter that merely elaborates on the obvious; however, it also suggests that, if applied wrongly, presuppositions can camouflage the duties and obligations placed on the subjects of a law and thus impede its accessibility and its efficient and effective implementation.