This article seeks to map and explain the extent to which national legislators constrain discretion contained in European Union directives during transposition. To this end, we use standard hypotheses from the domestic delegation literature regarding the necessity of policy conflict and transaction costs. Our empirical approach is based on a focused comparison of the transposition of several provisions of the Asylum Reception Conditions Directive in France, Germany, and the Netherlands. In order to capture content-specific aspects of discretion we employ an innovative measurement tool, the so-called Institutional Grammar Tool. The study shows that while all three states formally comply with the directive, the level of European Union discretion delegated to practical implementers varies considerably across the cases. Standard delegation theory cannot fully explain the patterns. Instead, existing delegation theories have to be adjusted to the transposition context, by accounting for domestic preferences regarding the status quo.