The control of foreign direct investments has rapidly gained importance in light of geopolitical tensions. With Regulation (EU) 2019/452, a regulatory framework for investment control at the level of Union law was introduced for the first time. This work aims to systematically capture the normative justification for the control of foreign direct investments and its interconnection with national administrative law. In addition to embedding the regulation within the system of the European Union and Union law, there will be an in-depth examination of the protected interests of the review process as well as the new cooperation mechanism between member states and the European Commission. The remaining regulatory powers and leeway of member states will be illuminated based on the provisions of German foreign trade law. On this basis, the system-forming elements of European control over foreign direct investments will be elaborated. A comprehensive treatment of the doctrinal foundations of investment control law and its practical legal implications will be provided. A systematic presentation of investment control within the EU multi-level system will be included, taking into account current developments in national foreign trade law, including innovations from the 17th amendment to the Foreign Trade Ordinance.