Why is soft law followed if it is non-binding? This question is addressed theoretically by highlighting that an instrument that is non-binding in the legal form can nevertheless contain enforcement measures, which make it ‘binding’ on a different level. These enforcement measures can be causally linked to national-level usage of EU soft law by drawing on three behavioural logics: enforcement, management and persuasion. Empirically we proceed in two steps. First, we systematically categorise a large number of EU soft law instruments and find that despite being non-binding, EU soft law instruments frequently contain hard and soft enforcement measures. Second, a survey experiment among national civil servants shows that instruments with enforcement measures are indeed perceived as more binding at the national level. Three case studies complement this data by illustrating how soft enforcement can play out through persuasion or management while hard duties push soft law usage through an enforcement logic.
