The purpose of a regulatory impact assessment (RIA) is to identify alternative solutions to address a policy problem, indicating both the positive and negative effects of each policy option. A well-executed assessment improves the transparency of the legislative procedure, and therefore increases trust in the legislator. In a later stage, the law for which the impact assessment was drafted can be brought for the Belgian Constitutional Court in an annulment procedure. This study will examine if the Belgian Constitutional Court, implicitly or explicitly, takes elements of the impact assessment into consideration during its appreciation of the constitutionality of the law. Moreover, the quality of the impact assessments will be analyzed which allows to determine if there is a relationship between the quality of the RIA and the conclusion on the constitutionality by the Constitutional Court.