This article deals with constitutional identity review by the German Federal Constitutional Court (FCC). While identity review is often discussed merely as an instrument of judicial contestation by which the FCC challenges the European Court of Justice and its stance on the primacy of EU law, this article shows that both the aim and the effect of identity review go far beyond judicial conflict. In fact, identity review produces significant preventive and deterrent effects on (national) EU policies, which come into play well before any judicial conflict. By means of preventive identity review, the FCC has created a fog of identity, a dark field of potential unconstitutionality, which considerably limits the scope of policy choices in advance and even irrespective of whether or not these policies would ultimately be judged to be unconstitutional. As for the defensive dimension of identity review, the article addresses the complexity of the (too often simplified) conceptual relationship of identity review to other modes of review such as ultra vires review and the Solange case law. It shows that identity review has gradually become the conceptual heart of the FCC’s defensive triad.