3 June 2024

EPO oppositions and appeals: an update

After a patent is granted by the EPO, there is a nine month period during which the grant of the patent can be opposed by any third party, initiating opposition proceedings. Once a decision has been reached in that process, any party unsuccessful in the opposition proceedings may file an appeal against the decision, initiating appeal proceedings.

There have been significant changes for opposition and appeal proceedings at the EPO over the last ten years. The procedures used to be very slow and, consequentially, it was not uncommon for patents to be nearing their expiry before a final decision was reached. The situation was exacerbated by a tendency for cases to bounce back and forth between the Opposition Division and the Boards of Appeal, and also by the growing backlog of cases caught in the proceedings.

In 2016 the EPO introduced their “Early Certainty from Opposition” initiative, aiming to reduce the average length of the opposition procedure to 15 months. The EPO has also tried to select only experienced Examiners to handle oppositions, for consistency of processing and results. Similarly, in 2020, the Boards of Appeal at the EPO introduced rule changes aimed at speeding up the appeal procedure (see article here), focusing on a review of the opposition decision rather than providing an opportunity to re-run the opposition, and trying to avoid cases bouncing between opposition and appeal and back again. More staff have also been appointed to the Boards of Appeal, with the aim of clearing the backlog of cases, and further rule changes were made earlier this year (see article here).

There has been some success from these initiatives. By the end of 2022, the mean processing time for a standard opposition had been reduced to 19.6 months (see Figure 1 from, and the Boards of Appeal are now consistently settling significantly more cases than are being filed (see Table 1 from such that the backlog of cases at the Boards of Appeal is being reduced (see Figure 2 from The improvement is noticeable in the cases we handle.

Figure 1: Timeliness of Opposition cases

Figure 2: Percentage of pending cases older than 30 months at the Boards of Appeal

Table 1: Number of new and settled cases at the Boards of Appeal, by type of procedure and technical field

Oral Proceedings by Video Conference

The COVID lockdowns jeopardised the improvements in timeliness that the EPO was working to achieve in the opposition and appeal procedures. In particular, each party has a right to request oral proceedings so that they can argue their case before a decision is reached. These oral proceedings were generally held in-person and so the lockdowns stopped the oral proceedings being held. To allow the EPO to progress cases again, the holding of oral proceedings by video conference was broadly introduced and imposed.

Whilst there was considerable trepidation initially, the implementation of video conference in oral proceedings is broadly considered a success. The EPO have worked with the Zoom provider to develop a specialised and optimised format, for example enabling the services of the EPO translators when parties are speaking different EPO languages. They also provide improved accessibility, since parties and the public can attend the proceedings from anywhere in the world.

Indeed, video conference is now widely used in opposition proceedings, being the default unless there are good reasons for them to be held in-person. At the Boards of Appeal, 57% of oral proceedings were held by video conference in 2023, reflecting the fact that the Boards of Appeal may be more likely to require in-person attendance depending, for example, on the preference of the members of each individual board.

Plausibility and Priority

When there are conflicting decisions on points of law from the Boards of Appeal, or if a point of law is considered to be of fundamental importance, the point of law may be referred to the Enlarged Board of Appeal for a decision that is then considered binding on the Boards of Appeal. The two most recent decisions from the Enlarged Board concern plausibility (G2/21) and priority (G1/22).  A detailed discussion of these decisions is beyond the remit of this article; reporting of the decisions may be found here and here (plausibility) and here (priority).

The plausibility decision, essentially, concerned whether it is possible for an applicant or patent proprietor to use data published after the filing date of the application or patent to support an argument for inventive step. Rather than providing a definitive answer, the Enlarged Board in G2/21 provided somewhat ambiguous guidance about what should be considered to decide whether such post-published evidence should be allowed to support inventive step, or not. Details of how to interpret this guidance is, therefore, being slowly revealed as Boards of Appeal release decisions in which they have applied it. There remains considerable uncertainty, although it seems post-published data may often be relied on so that the situation is similar to before G2/21 issued, albeit slightly more in the applicant or proprietor’s favour.

The priority decision assessed under what circumstances the priority of an application or patent may be challenged when it is argued that the applicant(s) did not own the priority rights in the priority application on the date the subsequent application was filed. This decision appears to have caused a significant change at the EPO. The Enlarged Board stated there is a “rebuttable presumption” that a priority claim is valid, and that “substantial factual indications to the contrary” are required to overturn that presumption. Reports of subsequent decisions from the EPO suggest that it will now be extremely difficult, if not impossible, to challenge priority on the basis of ownership, in almost all circumstances. This is a significant change, and we can expect to see fewer challenges on this basis at the EPO in the future. Of course, we do not know if each of the national courts in Europe, or the Unified Patent Court, will adopt a similar position.

Prior Use

Referral G1/23 is currently pending at the Enlarged Board.  The referral has been made by the Board of Appeal for case T 438/19.  A detailed reporting of the referral may be found here.

In summary, in order to decide whether the patent at issue in T 438/19 is inventive or not, it is necessary for the referring Board to assess what information was available as part of the state of the art at the relevant date of the patent. A particular product was commercially available at that date, and there was technical information available about that product, but it was argued that there was insufficient information to allow the skilled person to reproduce the product. The questions referred to the Enlarged Board of Appeal ask to what extent the prior availability of such a non-reproducible product, and its technical information, can be taken into account in the assessment of inventive step.

We await the outcome of this referral. When it issues, the Enlarged Board’s decision may be particularly relevant to those who produce products that are difficult to reverse engineer or reproduce, and those who currently deliberately withhold information about their commercial products, for example relying on trade secret protection.

Claim Interpretation and the Description

There is currently a tension at the EPO regarding the importance of the description in interpreting the scope of the claims.

In recent years, EPO Examiners, in both Examining and Opposition Divisions, have been demanding increasingly more substantial amendments to the description of an application or patent, to ensure that the description does not suggest that the scope of protection extends beyond that of the amended claims. The Boards of Appeal have not always agreed with this position on description amendment, as discussed here. It is likely that the concerns from Examiners arise from the national courts interpreting descriptions of patents to include equivalence of terms in the claims, when assessing scope of protection for infringement purposes.

Yet despite the emphasis that EPO Examiners are placing on the importance of the description, in numerous decisions the Boards of Appeal have found that when the terms of the claims are clear to the skilled person, the description should not be used to interpret the claims, even if this would change the meaning understood from one or more terms in the claims. Such a stance has been particularly impactful in decisions T 1473/19 and T 1127/16, in which the underlying patents were revoked due to added subject-matter, because amendments made during prosecution suggested a claim meaning contrary to the application originally filed, and the Board of Appeal would not allow the description to be used to interpret the claims.

We expect to see development of this area of law, and the Board deciding case T 439/22 has said they will refer questions to the Enlarged Board. The validity of the patent underlying this case depends on whether the description is used to interpret the claims or not, as a feature in the claims will encompass a prior art disclosure if the feature is given the unusually broad definition provided in the description. The Enlarged Board would need to decide whether the feature should be given that broad definition, or not.

Whilst we await the result of that decision, applicants at the EPO should carefully consider the meaning of the terms in the claims of their applications and try to avoid relying on definitions in the description, if possible. Care should also be taken to avoid any unintentional changes in the understood meaning of the claims when amendments are filed during prosecution of the application, particularly if the amendments are suggested by the Examiner; in T 1473/19 , at least, the patent was revoked as a consequence of amendments presented by the Examiner in the last stage of prosecution.

If you have any questions about the EPO opposition and appeal procedure, please do not hesitate to get in touch with us.