Appeals are for players: The limits of intervention in EPO proceedings

You’ve got to be in it to win it. At least, that’s according to a recent decision by the European Patent Office’s Enlarged Board of Appeal, which confirmed that interveners in Appeal proceedings following an opposition cannot become appellants in their own right if the original appellant withdraws. In other words: appeals are for the players, and if you did not oppose, you’re not in the game.

How can a patent be opposed in Europe?

When a European patent is granted, other parties have a nine-month window in which to oppose and challenge that patent centrally at the European Patent Office (EPO).

This phase is critical for competitors that wish to invalidate, or narrow the scope of, a granted patent that limits their own ability to commercialise competing technology, as it offers a cost-effective first port-of-call before resorting to litigation. Sometimes, for patentees, it can also be a useful opportunity to reinforce the strength of their patent claims.

In either case, opposition proceedings before the EPO provide both parties with legal certainty via decisions that are made by an independent opposition division.

What is an intervener?

An intervener is a third party that joins opposition proceedings after the nine-month window has passed. Not every party is entitled to do this, however.

Under the European Patent Convention (EPC), an intervener can only join opposition proceedings if the patentee has commenced legal action against it for infringing the patent being opposed or if an intervener has initiated proceedings for ruling that it is not infringing a patent following a request by the patentee to cease an alleged infringement.

If an intervention is ruled as admissible, it is treated as an opposition. This means that the intervener will have the right to introduce new arguments and prior art to the opposition.

What rights does an intervener have to appeal?

If a party to opposition believes that an opposition decision was flawed, whether legally, procedurally or evidentially, they may appeal it.

Exactly who can appeal a decision, however, is limited by Article 107 EPC to parties that were adversely affected by the opposition and that were part of the original proceedings. This could, therefore, include both the opponent and the intervener.

That being said, a third party that is accused of infringement, but that was not party to the original opposition proceedings, can also intervene in appeal proceedings following opposition under Article 105 EPC.

This intervention grants the intervener the right to participate in the appeal in a similar manner to the opponent in the original opposition.

Crucially, however, according to a decision in G 3/04, an intervener at the appeals stage does not acquire appellant status in the same way that an intervener in the original opposition proceedings does. 

This means that, if all other appellants withdraw their appeals, the appeals intervener cannot continue the appeal as an appellant in its own right. 

What is the difference between intervening during opposition and intervening during appeal?

Should an appeals intervener have the right to continue an appeal?

The case law in G 3/04 has been challenged on several occasions, most recently in case T 1286/23.

T 1286/23 involved an opposition that concluded with the patent being maintained in an amended form. Only one opponent subsequently appealed, with another party successfully intervening at the appeals stage.

When the opponent withdrew its appeal, however, the intervener was left as the sole party wanting to continue the appeal.

This led to the referral G 2/24, wherein clarity was sought from the EPOs Enlarged Board of Appeal (EBA) on whether an intervener to an appeal should, in fact, have the right to continue the appeal after the original appellant has withdrawn.

The EBA upheld its original position, stating that:

“After withdrawal of all appeals, proceedings may not be continued with a third party who intervened during the appeal proceedings in accordance with Article 105 EPC”

and that

“The intervening third party does not acquire an appellant status corresponding to the status of a person entitled to appeal within the meaning of Article 107, first sentence, EPC.”

What are the strategic implications of this decision?

The EBA’s ruling reinforces the procedural boundaries of intervention during appeal proceedings by emphasising that, whilst third parties can join appeal proceedings under specific conditions, they cannot take over an appeal once the original appellant withdraws.

In other words: once the game is forfeited, the players on the bench will not get a chance to play on the pitch.

Ultimately, this decision is good news for patent proprietors, as it both strengthens their position and provides a means of neutralising third-party interveners that join at the appeal stage through out-of-court settlements.

Whilst some may view this as an unfair advantage for the patentee, G 2/24 essentially emphasises the importance of respecting established legal frameworks, rather than attempting to create new legal rights.

For third parties, the message is clear: timing is everything. To avoid being sidelined, companies must proactively monitor their competitors’ patents and ensure that they use the nine-month window to oppose a granted patent or, at the least, intervene in an opposition before it reaches the appeals stage.

Rely on others to challenge a patent, and you risk being left to watch from the stands, unable to play when it matters most.