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The Research Group addresses illegality in the context of international peace and security law from a handful of complementary angles.

  • Establishing a typology of illegality

    First, the project sets out to reach a differentiated understanding of forms and facets of illegal actions. It does so by establishing and refining a typology of illegal actions that will uncover the various effects and functions violations of the law fulfil, including from a perspective of the sources of international law. The project researches the nuanced modes that international legal doctrine and practice have established in order to integrate these forms of illegality into the functioning of the overall system.

  • Mapping state practice from 1945-present

    In parallel to the drawing up of an illegality typology, the team undertakes an extensive study of state practice related to armed conflicts since 1945. The analysis shall reveal what states have been contesting in actual conflicts and with which legal arguments. This in turn, shall inform the broader typology of illegality, in particular the prevalence of the respective types of illegality in the practice of states. The analysis will also reveal when and under which circumstances challenges to the law turn out to be 'successful', i.e. result in a change of existing legal principles.

  • Approaching the (il)legal use of force through the lens of legal empirics

    Many norms on international peace and security are indeterminate. Thus, in a concrete context, the meaning of these norms depends chiefly on interpretation. State representatives are paramount in this interpretative exercise as they help to articulate what is considered legal or illegal by their State in a given situation.

    Therefore, this part of the project uses legal empirics to explore the different interpretative patterns and their importance for the evolution of peace and security law. By conducting semi-structured interviews with a representative sample of diplomats we will identify the main factors impacting on the interpretation of indeterminate norms by state officials. The aim is to identify the different approaches to international law, existing and emerging dividing lines, and the diverging use of international law which can be found in the various legal cultures.

  • Crafting a theoretical framework

    Finally, we work  on elaborating an overarching theoretical understanding of illegality. We link our doctrinal and empirical findings to the broader discourse, also in other disciplines. Especially international relations theory has extensively studied the effects of contestation and deviance and therefore provides an important point of reference also within the legal discourse.