The constitutional law of external security: Military operations in the face of new security threats

• Applicants: Professor Dr. Christian Marxsen; Dr. Alexander Wentker
• Subject Area: Public Law
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 573012710

The foreign relations of the Federal Republic of Germany and Europe are undergoing radical change. As the United States‘ security guarantee in Europe comes to an end, fundamental questions about the direction of foreign policy and the options for action in this new geopolitical situation are becoming increasingly urgent. This research project addresses key aspects of this changed situation: it analyses the constitutional framework for new forms of military operations and aims to identify and consolidate the relevant constitutional principles in the field of external security. Changing threats and the proclaimed “Zeitenwende” in German security policy are shifting and expanding the types of operations to be carried out by the Bundeswehr. The project examines how existing constitutional law provisions can be applied to new forms of military operations, such as the military response to so-called hybrid threats (e.g. through ‘shadow fleets’ targeting maritime infrastructure or threats by unmanned drones) or the permanent stationing of Bundeswehr troops abroad. All forms of deployment are also becoming increasingly technology-driven. The project investigates how the constitutional framework for the deployment of the Bundeswehr can be applied to the use of new technologies. The use of artificial intelligence for the resort to military force is particularly problematic, and debate from a constitutional law perspective is lacking so far. The constitutional law issues at stake are fundamental. The issues include the application of fundamental rights and the safeguarding of the Bundestag‘s responsibility to exercise control. Beyond considering specific forms of deployment, the project aims to determine the special features of the structural principles of foreign relations law applicable to the field of external security, particularly with regard to the application of fundamental rights and the separation of powers. The project is based on the observation that a considerable transformation is currently taking place, which can be described as a constitutional ‘normalisation’ of foreign relations law. ‘Normalisation’ refers to tendencies towards a departure from the long-dominant exceptionalism, according to which fundamental constitutional principles must be severely restricted in their effect on foreign policy. There is considerable potential for tension here between the capacity to act in foreign policy and increasing judicialisation. It is therefore important to fine-tune the principles in a way that is also sensitive to the different contexts and requirements of the exercise of sovereign power at home and abroad. The hypothesis is that the required capacity to act can then be largely accommodated within the framework of existing general constitutional doctrine, for example with regard to duties to protect.

• DFG Programme: Research Grants