Upholding the Rule of Law as a Non‑Negotiable Condition of EU Membership

In this paper, I wish to focus on the rule of law not merely as a foundational value set out in Article 2 TEU, but as a non‑negotiable requirement for membership, and, in that regard, on the crucial intersection between the internal constitutional order and the accession dimension. Article 49 TEU stipulates that any European state applying for membership must respect the values referred to in Article 2 TEU and be committed to promoting them. Since the Court’s Repubblika judgment (Case C‑896/19), we also know that adherence to these foundational values, including the rule of law, is the very basis upon which the functionality of the Union and the necessary mutual trust among its Member States are built, and is the condition for the enjoyment of all rights deriving from the application of the Treaties to that Member State (obligation of non‑regression). It is in this membership context that the requirement to respect the rule of law is normatively and functionally most evident, and that the imperative of consistency – an obligation grounded in Treaty obligations and the foundational requirements of the rule of law – is most salient. My central hypothesis is that the rule of law must be understood and applied consistently across Member States and candidate countries by EU institutions; the rule of law thus also acting as a constraint on the Union’s own conduct. Given the rule of law’s elevated status, its protection demands a higher standard of consistency than we could expect in other areas. Without consistent application, the rule of law cannot exist. Inconsistency and perceived “double standards”, and the politicization of rule of law enforcement, risk eroding the rule of law itself and leading to a loss of trust in EU institutions, potentially threatening the stability of the Union. Additionally, for the EU to position itself as a credible promoter of rule of law standards abroad, its institutional approach must consistently uphold this principle. The application of the rule of law is not a political question: there are clear legal standards and obligations stemming from the Treaties that need to be followed for the survival of the EU as a project based on shared values. In this paper, I investigate the following core questions: How do various EU institutions define and apply the rule of law as a condition for enduring membership? What is the minimum acceptable level of consistency in the EU’s interpretation and enforcement of the rule of law across Member States and candidate countries? The Treaty of Lisbon states in its Preamble an aim to improve the coherence of EU action. My central research question directly engages with whether and how the EU has achieved this consistency concerning the rule of law as a membership criterion since Lisbon.