Dr Niels Kirst, Assistant Professor of European Law at Dublin City University, Deputy Director of the DCU Brexit Institute

The European Defence Community (EDC), proposed in the early 1950s, represents a pivotal moment in the history of European integration and collective security. Aimed at establishing a supranational defence organization, the EDC Treaty sought to integrate the militaries of six founding members: France, Germany, Italy, and the Benelux countries. Considering the increasing security challenges for Europe due to the unlawful Russian invasion of Ukraine and the upcoming second Trump Presidency in the United States, it is worth asking whether the EDC would be open to the accession of new member States.

Legally, the EDC Treaty explicitly allowed for the accession by other European countries beyond the six founding members. Article 129 EDC provides that additional members could join the community, subject to having obtained an opinion of the Commissariat and the unanimous approval by the Council. According to Article 19 EDC, the Commissariat is an independent executive expert council appointed by the contracting member states. According to Article 39 EDC, the Council is conceived as the decision-making body by the contracting member States’ representatives – similar to the Council on the EU level. The accession clause, thus, reflects the understanding that European security challenges are not confined to the founding members and that expanding the EDC can bolster collective defence. The Treaty requires acceding members to align with the EDC’s objectives of shared defence responsibilities. It underscores the Treaty’s design to adapt to geopolitical shifts and the evolving needs of European security.

Taking inspiration from how enlargement works under the current EU Treaty framework allows to imagine the accession procedure under the EDC. Procedurally, the first step is to submit an application for membership to the EDC Council (“Any European State may request to accede to the present Treaty.”). This would usually done by a letter submitting a formal accession request. This first paragraph of Article 129 EDC also gives the first condition to membership, as it speaks of a “European State”. Similar to Article 49 TEU, this indicates that only states geographically located in Europe may join the EDC. Next, the unanimous agreement by the current members is a conditio sine non qua for the potential accession of a new member (“The Council, after having obtained the opinion of the Commissariat, shall act by unanimous vote, and shall also fix the terms of accession by unanimous vote.”). The institutions that would be mainly involved would be the EDC Commissariat (independent expert council of 9 appointed members), issuing a non-binding opinion, and the Council (6 representatives of the founding members), approving the application for accession by unanimous vote. Only if all six founding members unanimously agree to it, is accession possible. 

Going forward, the EDC Council also determines the “terms of accession”. This indicates that an accession treaty would need to be drafted similar to the accession treaty in the EU enlargement procedure. Of course, the EDC would need to be prepared to integrate a new member into the operational capabilities of the defence pact. Therefore, the accession treaty would ensure that integration between the old and a new member runs smoothly and is streamlined. As a final step, the accession of a new member may also require the acceding country’s ratification of the accession treaty and the EDC Treaty with respect to the national constitutional requirements of that country. This could mean a ratification by both chambers of parliament. Ultimately, the signed accession treaty would need to be sent to “the Government acting as depository of the Treaty”, which would be the French government in the case of the EDC (see Article 130 EDC Treaty). With this, the accession of a new member would become effective (“Accession shall become effective ·on the day on which the instrument of accession is received by the Government acting as depository of the Treaty”). 

What makes the EDC so special? A clear added value is that the EDC’s founding members could establish high accession thresholds by applying similar criteria, such as those under the current EU enlargement policy, e.g., respect for the rule of law and fundamental rights under the Copenhagen Criteria. This would also allow the exclusion of EU Member States, such as Hungary, that do not respect the rule of law and have proven to be a Trojan horse within the EU. Advantageously, accession to the EDC would be open to non-EU Member States that respect EU values and are interested in defence integration, such as the United Kingdom and Norway. Overall, the EDC Treaty’s openness to accession suggests that it is designed to accommodate an evolving and expanding membership. The EDC, therefore, aligns with ongoing discussions about expanding European security frameworks, particularly in the context of heightened geopolitical tensions following Russia’s unlawful invasion of Ukraine and Trumps reelection in the United States. In conclusion, the EDC Treaty provides a legal mechanism for the accession of new members, showcasing its potential as a scalable and inclusive defence framework.