Effectiveness in Law: How Norms Engage with Facts in European and International Law. The research project explores the role of effectiveness in legal discourse. The main objective is to offer a better understanding of the functions of effectiveness in European and international law (epistemology of effectiveness). It does so by examining different expressions of effectiveness (phenomenology of effectiveness): the ‘effet utile’ principle in the interpretation of legal norms, the ‘effects doctrine’ with respect to questions of jurisdiction, and ‘effective protection’ in the context of fundamental and human rights. Finally, effectiveness is operationalized through ‘impact assessments’ (methodology of effectiveness). In contrast to an empirical perspective that observes the effectiveness of law in the social and political realm, this project examines effectiveness in law from a theoretical perspective (narratives of effectiveness). Where does law itself refer to effectiveness, and what legal consequences does it derive from it? To what extent can the effects doctrine justify extraterritorial legislation? And how do impact assessments change our understanding of law? The research project thus addresses the relationship between facts and norms and their mutual impact. The underlying conceptual constellations are: (1) the normative force of the normative, which concerns the prescriptive function of law (‘law is counterfactual’); (2) the factual force of the normative, which covers the regulatory function of law (‘law as social engineering’); and (3) the normative force of the factual, which deals with the perpetuating function of law (‘effectiveness as law’).