EU treaty reform: the debate that won’t go away — and probably shouldn’t

For most of its post-Lisbon history, EU treaty reform was a topic for academics and Verhofstadt-style federalists. Mention it in the Council, and ministers would mutter about the trauma of the 2005 constitutional referendums. The Lisbon Treaty was meant to be the settlement that lasted a generation. Two years into the post-2022 strategic environment, that settlement is showing serious cracks — and the treaty reform conversation has moved into the policy mainstream.

What is broken

Three problems sit at the heart of the current debate. First, unanimity: in foreign policy, taxation, and several other areas, every member state has a veto. In a Union of 27, that has produced episodic paralysis on Russia sanctions, on Hungary’s rule-of-law breaches, on tax reforms, and on enlargement-related decisions. In a Union of 30+ — the realistic mid-term picture — unanimity is, at best, a recipe for further delay.

Second, institutional balance: the European Parliament’s powers have grown, but the relationship with national parliaments and with the Council remains awkward. The Conference on the Future of Europe (2021-22) produced 49 proposals on this; the formal follow-up has been thin. Third, capacity and speed: the EU’s response times on crises — pandemic, energy shock, security shock — have improved, but they remain structurally slower than the threats they face.

The reform proposals on the table

Several concrete proposals have moved beyond the think-tank stage. The Franco-German report on EU institutional reform, published in 2023, proposed extending qualified majority voting (QMV) to areas now covered by unanimity, particularly in foreign and security policy. The European Parliament’s resolutions have repeatedly called for treaty change to address rule-of-law enforcement, fiscal governance, and the Spitzenkandidat process. National constitutional courts, particularly in Germany, have produced rulings that constrain the political space for some changes — but not all.

The procedural reality

Treaty change requires unanimity among member states and ratification by all of them — typically through national parliaments, sometimes through referendums. That bar is high, and lessons from the 2005 referendums in France and the Netherlands still shape political calculation. Passerelle clauses — provisions in the existing treaties that allow the move from unanimity to QMV in specific areas, by unanimous decision of the European Council — are an underused alternative. They have been on the books since 2009 but have rarely been activated.

The enlargement linkage

The most concrete pressure for reform comes from enlargement. A 33-member Union will struggle with unanimity even more than a 27-member one. Many in Brussels have argued — convincingly, in our view — that internal reform and enlargement must be sequenced together, not as a sequence of internal reform first and then enlargement, but as parallel tracks. Otherwise, the EU risks either reform without enlargement (a failure of strategic imagination) or enlargement without reform (a recipe for paralysis).

The case for the conversation

Treaty reform is hard, and the politics are unforgiving. But avoiding the conversation is not free either. Every paralysed sanctions package, every veto on rule-of-law action, every multi-year fiscal governance dispute, is a reminder that the existing architecture is producing outcomes the EU’s own treaties say it should not produce. The case for reform is not that the EU is broken. It is that the EU works less well than it should — and that this matters more, not less, in the strategic environment that 2026 has delivered. The honest debate is the one worth having.