The Use of Force in Practice: 1945-2020

The dataset on “The Use of Force in Practice: 1945-2020” provides a comprehensive compilation of data about how international law related to the prohibition of force has been invoked regarding armed conflicts between 1945 – 2020. It covers the claims (legal and non-legal) that actors (states as well as non-state actors) have invoked as justifications for the participation in these conflicts under the jus contra bellum. The dataset also explores the substance of disputes, as well as international reactions to these conflicts. The dataset contains data of 81 major conflicts with an international dimension fought between 1945 to 2020 and provides a detailed assessment of the justifications invoked by overall 320 parties to these conflicts. The list of conflicts is available as Annex I. The raw data is compiled in 81 case notes (Annex IV). The analytical grid for the analysis of conflicts (Annex II) and the codebook (Annex III) are available. The data is compiled in a Microsoft Excel file (Annex V) and is presented in two ways. Table 1 presents the data actor-focused, i.e. structured regarding the 320 identified conflict parties. For each conflict party, we present the claims advanced, categorize the disputes regarding those claims, and the international reactions towards the conflict party’s claims and behavior. Table 2 presents the data in a conflict-focused way. For each of the 81 conflicts, we aggregate the claims, disputes, and international reactions. The rules for data aggregation are detailed in the codebook. When using the data, always cite: Christian Marxsen and Florian Kriener, The Use of Force in Practice: 1945-2020, British Yearbook of International Law (2026). The data was collected between 2018 and 2023 at the Max Planck Institute for Comparative Public Law and International Law by researchers of the Max Planck Research Group “Shades of Illegality in International Peace and Security Law”, led by Christian Marxsen.