In the European Union, the implementation deficit arises when Union legislation is implemented at varying degrees or not at all. This problem is a common occurrence in the field of EU environmental policy. Although results of the directive are binding, some Member States do not comply with their obligation. In this article, the cases of the national implementation of the Restriction of Hazardous Substances Directive (RoHS) in the Member States Germany and United Kingdom are examined. It sets out to describe the influence of national regulatory styles and structures in the two countries on EU law implementation. Through the lens of historical institutionalism, this paper asks the question:“why are some member states able to implement EU directives more easily than others?”. The article argues that since it is more similar to the EU regulatory styles and structures, the German government can implement environmental policy more easily than the UK government. Consequently, an implementation gap occurs, not through the Member States’ unwillingness to comply, but due to limited capabilities to implement.