Ana Herrera Arroyo. Director of Patents, Technological Development and Innovation at PONS IP | European Patent Attorney.

Decision G 2/24 of the Enlarged Board of Appeal of the European Patent Office (EPO), handed down on 25 September 2025, has definitively settled a recurring debate concerning appeal proceedings: the possibility for a third party who has only intervened at the appeal stage to continue the proceedings following the withdrawal of the appeal by the original appellant.

The case on which this decision is based, known as the FOREO (“Skin cleanser”) case, is of great practical and strategic value to patent proprietors, opponents and assumed infringers before the EPO.

The dispute centres on European patent EP 2 941 163, relating to a skin cleansing device, owned by FOREO.

During the opposition phase, Beurer challenged the patent. The Opposition Division decided to uphold the application as amended, in a version favourable to the proprietor. In response to that decision, Beurer lodged an appeal.

At the same time, Geske, having received a warning letter regarding an assumed infringement, attempted to intervene in the proceedings. However, their intervention was not admitted during the opposition phase, but was subsequently admitted at the appeal stage, pursuant to Article 105 of the European Patent Convention (EPC).

The turning point in the case came when Beurer withdrew their appeal. The key question, then, was whether Geske—who had only been involved at the appeal stage—could continue the proceedings on their own.

The final ruling came in decision G 2/24, in which the EPO’s Enlarged Board of Appeal (EBoA) ruled that it could not do so. As a result, the decision of the Opposition Division upholding the amended patent in favour of FOREO stood.

Two questions were put to the EBoA: essentially, whether, following the withdrawal of all appeals, the appeal proceedings may continue solely with a third party who has intervened at that stage under Article 105 EPC, and whether that third party may acquire the status of appellant within the meaning of Article 107 EPC.

The Enlarged Board ruled against both questions, expressly reaffirming the doctrine previously established in decision G 3/04.

There are four key grounds for the decision. On the one hand, the appeal as a judicial procedure. The Enlarged Board emphasises that an appeal to the EPO is not an extension of the opposition proceedings, but an autonomous judicial procedure, the purpose of which is to review a decision that has caused specific procedural prejudice to a particular party. If the appellant decides to withdraw their appeal, the very purpose of the proceedings ceases to exist.

On the other hand, the principle of party disposition. Ruling G 2/24 reinforces the principle that it is the parties who determine the existence and scope of the appeal, meaning that the EPO cannot continue proceedings on its own initiative or at the request of a third party once there is no longer a pending appeal. This principle prevents an intervener from keeping appeal proceedings “artificially alive”.

Furthermore, it is noted that there is no legal basis for a change in doctrine. The Enlarged Board thus points out that Articles 99, 105 and 107 of the EPC have not undergone any significant changes since decision G 3/04. Consequently, there is no legal basis for recognising the intervener in the appeal as having an autonomous procedural status. Any change in this regard would require an explicit legislative amendment to the Convention, rather than a reinterpretation through case law.

Finally, the ancillary nature of intervention (Art. 105 EPC) in appeal proceedings: Late intervention at the appeal stage remains strictly ancillary in nature, in the sense that it does not confer procedural autonomy, nor does it transform the intervener into an appellant; such intervention is always contingent upon the existence of at least one valid and pending appeal.

This decision is primarily confirmatory and clarifying in nature, but it is of enormous practical significance. Firstly, it definitively establishes that an intervener at the appeal stage is in a dependent procedural position: if all the appellants withdraw their appeals, the proceedings are automatically terminated.

Secondly, it reinforces a strict interpretation of the concept of “appellant” (Article 107 EPC): only a party to the proceedings that gave rise to the contested decision and who has been adversely affected by it may be an appellant. The intervener does not meet these requirements.

From a strategic perspective, G 2/24 implies that trusting in a late intervention is highly risky. Thus, an assumed infringer who has not intervened in time (at the opposition stage) may be left with no effective remedy before the EPO if the original opponents decide to withdraw at the later appeal stage.

From a legal standpoint, G 2/24 and G 3/04 are identical: once all appeals have been withdrawn, the proceedings cannot continue with an intervener. The key contribution of G 2/24 is that it directly addresses the criticisms levelled against G 3/04, making it clear that mere doctrinal disagreement does not justify a change in case law, that there have been no relevant legislative changes, and that any expansion of the intervener’s role would require an amendment to the EPC. In this regard, G 2/24 definitively shields the doctrine set out in G 3/04.

In conclusion, Decision G 2/24 does not introduce a new paradigm, but definitively consolidates the existing one by confirming that intervention at the appeal stage is ancillary, dependent and not autonomous, reaffirming the strict concept of an appellant and providing clear legal certainty to the EPO’s appeal system. If you don’t intervene in time, you may miss out on the proceedings.