In a recent letter addressed to the Cypriot Council Presidency and the leaders of the European Commission and the European Council, German Chancellor Friederich Merz proposed a status of “associate membership” for Ukraine. This “innovative solution” is presented as an intermediate step towards full membership. It envisages, amongst others, Ukraine’s participation in the EU’s main institutions but without voting rights or dedicated portfolio; an extension of the EU’s “mutual assistance” clause (Art. 42(7) TEU) as a security guarantee for Ukraine and a “snap-back mechanism” that could be triggered in case of Ukraine’s backsliding in democratic and market economy reforms.

The German proposal is not the first and most likely not the last of this kind. It echoes earlier suggestions about “reverse enlargement”, proposed by Commission President Ursula von der Leyen, and ideas about “staged integration” floated in academic circles. The main objective of all those proposals is to ensure continuous support for Ukraine’s reform efforts in the understanding that obtaining full membership is a long and cumbersome process. Providing an “intermediate” and “tailor-made” status for Ukraine aims to overcome a tension between the political imperatives of enlargement as “a geopolitical necessity” on the one hand, and fulfilment of the formal requirements for membership on the basis of an objective and merit-based process, on the other hand. Moreover, it comes at a time when the EU envisages a more prominent role in any future peace negotiations between Russia and Ukraine.

Whereas the political inspiration of Merz’s proposal is clear, its translation into practice raises significant questions. The letter proceeds from the assumption that the granting of an “associated membership” status for Ukraine is possible on the basis of “a strong political agreement” and without a ratification of an Accession Treaty or any EU Treaty changes. This assumption is, arguably, the weakest part of the entire document.

An Ambiguous Legal Status

A status of “associate membership” without a clear legal basis may be perceived as a form of “window-dressing” offering a symbolic type of second-rate or fake membership without real, substantive rights. Ukrainian President Zelensky already hinted at this risk when he stated that “Ukraine does not defend Europe partially, therefore it deserves full membership”. He also emphasised that “without Ukraine there can be no real European project, thus the presence of Ukraine in the EU must be real too”. Vice-Prime Minister for European integration of Ukraine, Taras Kachka, further commented that the proposal of German Chancellor Merz can only be considered as complimentary to achieve the objective of full EU membership but not as an alternative format even though he acknowledged that different mechanisms can play a role in the EU accession process. One aspect of the proposal received a more positive reaction among Ukrainian political and expert communities. This is the suggestion to allow Ukrainian representatives to work in EU institutions either on an informal or formal basis. It is believed that the sooner Ukraine embarks upon this process and develops domestic political and legal mechanisms for a transparent selection of candidates, the better. For instance, it took many years for Ukraine to set up a transparent and well-functioning system for the selection of candidates for the office of judge at the European Court on Human Rights in Strasbourg. Further, Ukrainian civil servants and experts with experience of working and dealing with EU institutions could considerably enhance the quality of the EU accession process of Ukraine.

The key question, however, is how the envisaged status of “associated membership” can work in practice, The concept of “associated membership” has no legal basis in the EU Treaties and ambiguously combines the notions of “association” as foreseen under Article 217 TFEU and “membership” under Article 49 TEU.

The legal concept of association is very flexible and typically provides for various forms of integration without formal membership. A clear dividing line between the status of “association” and “membership” precisely concerns the participation in EU decision-making and full representation in the EU institutions. The latter is reserved for Member States only, in order to preserve the Union’s decision-making autonomy. Even participation without voting rights is, in principle, excluded for non-members, because their mere presence may already affect the deliberations. Accordingly, third-country representatives cannot be given a formal participatory role on the basis of an Association Agreement. There can only be an ad hoc participation, upon invitation and for a specific item on the agenda. In recent years, Ukrainian President Zelensky has been invited on several occasions to update the members of the European Council on the situation in Ukraine. This is, however, not to be seen as a formal participation in the European Council meeting. An invited third-country representative can only enter the room for a specific item and is not allowed to intervene or even be present during the deliberations. As observed by the Council’s legal service some time ago, this strict arrangement applies to all third countries irrespective of how closely their legal relations with the Union are and irrespective of their participation in the EU enlargement process. The only exception concerns the situation of acceding countries, which can act as observers in the interim period between the signature of the Treaty of Accession and its entry into force.

Hence, introducing a kind of “associated membership” which envisages participatory rights in EU institutions is legally impossible under Article 217 TFEU. A “strong political agreement”, as suggested in Merz’s letter, is arguably also not an option. As can be derived from the case law of the Court of Justice, non-binding arrangements must also respect the EU’s institutional balance and decision-making autonomy. The only feasible option is, therefore, to proceed on the basis of a Treaty on Accession, i.e. an agreement between the Member States and the applicant state as foreseen under Article 49 (2) TEU. Such an agreement includes “the conditions of admission and the adjustments of the Treaties on which the Union is founded”. Arguably, this provision gives the contracting parties a broad margin of discretion to define the precise terms of admission and required EU Treaty amendments, as long as there is a link with the actual enlargement of the Union. Granting new Member States a transitionary status without full voting rights in the EU institutions could perhaps be part of such an arrangement. As mentioned, previous enlargement rounds envisaged such an observer status for the period between the signature and actual entry into force of the Treaty on Accession. The main difference and challenge of the Merz proposal is related to the undefined period of the associated membership status. A long-term exclusion of new Member States from the EU’s decision-making procedures seems difficult to reconcile with the principle of equality between the Member States, as enshrined in Article 4(2) TEU. At the very least, a clear procedure and perspective towards full participation is warranted.

A Security Guarantee for Ukraine

The most substantive aspect of the German proposal concerns the possibility for Ukraine to request aid from other Member States under the mutual assistance clause of Article 42(7) TEU. This provision, introduced with the Treaty of Lisbon, has remained largely unexploited. It was triggered once, after terrorist attacks in France. Since the US attempts to acquire Greenland from Denmark and an Iranian drone attack on a British military base in Cyprus, the High Representative and the European External Action Service (EEAS) are working on the operationalisation of the clause.

The inclusion of Ukraine within the geographical scope of application of Article 42 (7) TEU would be a significant development. Again, the proposal of Chancellor Merz is very ambiguous in the sense that it envisages “a political commitment by the Member States to apply Article 42 (7) TEU”. The question here is how such a political commitment can be reconciled with the text and spirit of the EU Treaties. Article 42 (7) TEU explicitly refers to the situation where “a Member State is the victim of an armed aggression on its territory.” The mutual assistance commitment is an expression of the special bond between the Member States in a common legal order. It seems that an extension of this commitment cannot easily be done on the basis of a political commitment, particularly if this is deemed to create “a substantial security guarantee.” Arguably, such a guarantee requires the formal granting of an EU Member State status to Ukraine on the basis of a Treaty of Accession or, alternatively, the inclusion of a similarly worded provision in the EU-Ukraine Association Agreement.

Extending the “mutual assistance” clause to Ukraine is in any event a sensitive issue for the existing Member States. It is almost impossible to imagine such an extension at a time of active warfare between Russia and Ukraine because this would immediately involve all EU Member States in the conflict. A more plausible scenario is to offer this prospect as part of a future peace deal between Russia and Ukraine. In such a scenario, Article 42 (7) TEU could serve as the EU’s security guarantee for Ukraine against Russian military aggression in the future. This largely corresponds to some ideas that were included in a US-based draft peace proposal that was presented at the end of 2025. The offer of an accelerated Ukrainian EU membership was seen as an integral part of the envisaged compromise, but it quickly turned out that such a commitment cannot be upheld in view of a merit-based enlargement process and the procedural requirements of Article 49 TEU. An intermediate status of “associated membership” focussing on the inclusion of Ukraine in the EU’s mutual assistance clause aims to overcome this issue. Whether this can be done on the basis of a “strong political commitment” is, however, doubtful.

A ‘Snap-Back Mechanism’ as a Safeguard Against Backsliding

The idea of a “snap-back mechanism” in case of backsliding in respect for the EU’s fundamental values, most notably the rule of law, is the least controversial aspect of the proposal. In fact, this replicates the EU’s pre- and post-accession conditionality as gradually developed in the EU’s enlargement policy. The recent generation of EU negotiating frameworks with candidate countries, including Ukraine, already envisage a special procedure to counter backsliding in reform implementation. This implies that the Commission, either on its own initiative or at the duly motivated request of a Member State, can propose a suspension of the accession negotiations; withhold its recommendation to open or close other negotiating clusters and chapters; or recommend the re-opening of chapters that had been provisionally closed. The Commission’s proposal is deemed to be adopted by the Council unless it is rejected by a qualified majority within 90 days.

With respect to post-accession conditionality, the introduction of safeguard clauses in a Treaty of Accession can address concerns of potential backsliding after accession (in addition to the potential use of Article 7 TEU). As announced by Commissioner for enlargement, Marta Kos, the next Accession Treaty with Montenegro will contain even stronger safeguards than before. Hence, the inclusion of a mechanism countering potential backsliding in the proposal for “associated membership” hardly comes as a surprise. It is all but new and a confirmation of existing practice.

Conclusion

The proposal by German Chancellor Merz for “associated membership” is part of the ongoing debate over further EU enlargement and the EU’s role in providing security guarantees for Ukraine. It aims to reconcile the geopolitical necessity to do something for Ukraine without undermining the formal enlargement procedure. Whereas certain aspects of the proposal may sound attractive at first sight, the absence of a strong legal foundation or even an in-depth reflection about the legal translation of this political initiative undermines its credibility. The lukewarm response from Kyiv should not come as a surprise when there is a constant flow of general ideas and offers of symbolic membership.

A key concern is also that the envisaged “associated membership” is specifically designed for the situation of Ukraine. For the Western Balkan countries and Moldova, Chancellor Merz proposes “to look into innovative solutions also for those candidate countries”. This may introduce a new cleavage in the EU’s enlargement process, with a special arrangement for Ukraine, on the one hand, and the other candidate countries, on the other hand. Even though the situation of Ukraine as a country at war is indeed particular, the introduction of such a division entails the risk that Ukraine is left behind in its progress towards full membership.

Given the geopolitical significance of further enlargement, as emphasised time and again in official EU documents, it is striking that the discussion on how to proceed is still largely based on rather vague proposals. Whereas Ukraine and other candidate countries proceed with their reform process, the Union fails to properly do its own homework. Already in 2024, the European Commission announced a thorough assessment of required internal pre-enlargement reforms and policy reviews. The outcome of this exercise still needs to be communicated. When the EU is serious about enlargement, a substantive and comprehensive vision is required instead of a constant flow of political ideas.