From Stalemate to Solution: Rethinking EU Approaches to Bilateral Disputes in the Context of Enlargement

Although Russia’s full-scale invasion of Ukraine has given new momentum to the European Union’s enlargement process, further progress is being hindered by unresolved bilateral disputes.

In cataloguing the various disputes, this report distinguishes between disputes involving a member state and a candidate country, and those between candidate countries themselves, classifying them into categories such as statehood identity issues post-conflict issues, border demarcation and/or territorial disputes, minority rights protection, and economic issues. While many disputes exist among candidate countries, the more challenging ones for the EU to resolve are those which involve a member state. Member states can strategically misuse their veto power in the pre-accession process to gain political leverage over a candidate country, as currently seen with Bulgaria vis-à-vis North Macedonia and Hungary towards Ukraine. The authors argue that the ability to manage and resolve them is not merely a technical requirement for enlargement but increasingly a strategic necessity for the EU in a more conflicted geopolitical environment.

In reviewing past practice, the report highlights the EU’s non-interventionist approach before the early 2000s, noting how the EU itself served as a framework for cooperation and dispute resolution, as demonstrated in the case of Northern Ireland. Around the time of the ‘big bang’ enlargement of 2004, the EU’s approach underwent a shift, with the prior resolution of disputes increasingly becoming a condition for accession. However, this long-standing expectation warrants a critical re-examination in light of inconsistencies in policy application, stagnation in existing dispute settlement mechanisms, mounting blockades, and the rise of nativist populism in Europe.

The report assesses a wide range of EU instruments and third-party resolution mechanisms provided by the Council of Europe, United Nations, Organization for Security and Co-operation in Europe, and the Permanent Court of Arbitration. Existing proposals to overcome the misuse of veto power are also analysed.

The authors argue that a more strategic, consistent, and principle-based approach to dispute resolution—supported by legal tools, political incentives, and coordination with third-party actors—is essential to re-dynamise the enlargement process and sustain the EU’s credibility as a promoter of peace, stability, and integration. To that end, they emphasise that the Commission should abandon the habit of seeking unanimity at every interim step of the enlargement process, which is not prescribed by EU law, and that the EU should create an Enlargement Dispute Resolution Mechanism (EDRM) that separates between issues that fall under the aquis chapters for membership negotiations and those that should rely on external arbitration and mediation. Furthermore, they advocate that the EU should double down on its preventive efforts to manage latent bilateral disputes through early-warning diplomacy and structured dialogue.