Services Directive – Peculiar harmonisation technique – Unusual design – Key provisions giving rise to constitutional problems – Special derogation system – Freezing of the Rule of Reason – (In)compatibility with EU primary law – Appropriate legal basis? – Non–transposition by several member states – Arguments for a benign assessment of the Commission and the Court – Problematic enforcement in horizontal situations – Possible solutions and their shortcomings – Overall need for a flexible approach