This article examines implications of EU State aid law for tasks that a national court must undertake, may undertake and also tasks that they must not undertake because such tasks are in the jurisdiction of the Commission. It examines ways in which the Commission should be asked to assist the national courts; the questions that a national court should (or may wish to) put to the Commission and instances in which the Commission may wish to intervene as an amicus curiae. Interaction of substantive and procedural law at EU level with their counterparts at national level is seen to be important in ensuring that EU law is effectively and equivalently applied nationally.
Keywords: National Courts; Procedural and Interpretive Guidance; Amicius Curiae; Preliminary Ruling; Black Cabs.