EPO Referral May Shift Patent Description Amendment Rules

1. EPO's Unique Requirement for Patent Descriptions: The European Patent Office requests that patent descriptions be amended to conform with allowed claims to prevent inconsistencies, which contrasts with most global patent offices that only allow amendments to correct errors.
   
   
2. Impact of 2021 Examination Guidelines: The 2021 updated examination guidelines introduced significant changes, such as requiring descriptions to delete or mark as "not claimed" any embodiments not covered by allowed claims, and prompted applicants to question the legal basis for this practice.
   
   
3. Referral to the Enlarged Board for Clarity: Since divergent case law has been identified, there is now a referral to the Enlarged Board (G 1/25) to seek clarity on the legal basis for this practice.

On July 29, the European Patent Office announced referral G 1/25 to the Enlarged Board of Appeal concerning amendments to the description of a patent.

When prosecuting applications at the majority of global patent offices, the patent description is generally only amended to correct errors. In contrast, the EPO requires that the description is amended for conformity with the allowed claims before proceeding to grant. The EPO reasons that amending the description is needed to remove inconsistencies, which could otherwise result in a lack of legal certainty for third parties.

This practice has come into the spotlight in recent years following an update to the EPO's guidelines for examination, according to which examiners are now encouraged to issue a summons to oral proceedings if the description is not amended to the satisfaction of the examiner.

Some applicants responded by questioning the legal basis for this practice, and divergent case law has since appeared. The July 29 referral seeks to provide clarification on this question of alleged inconsistencies and the legal basis for description amendments.

Background

While the EPO requires the description to be amended to remove inconsistencies with claims that could result in a lack of legal certainty for third parties, would-be patentees rarely share this view. The rest of the world manages with descriptions that are often broader in scope than the final claims, and so applicants from outside of Europe often struggle to understand why this needs to be done at all.

From the applicant's perspective, it often feels like an unnecessary additional cost. Undertaking description amendments can be expensive, particularly in fields like chemistry and life sciences, where applications can run to hundreds of pages. Amending the description also has the potential to introduce errors.

These may be typographical, particularly if descriptions need to be recreated from online documents. Optical character recognition still tends to confuse "1" and "l," for example. More importantly, however, inadvertent added subject matter can be introduced, which may be problematic or even fatal post-grant.

A further complication is that there is no right way to carry out description amendments. Practice varies enormously between attorneys and practice areas. As an example, in the fields of chemistry and life sciences, attorneys may elect to delete examples falling outside the scope of the allowed claims.

This can significantly reduce the length of the specification, which can, in turn, reduce the costs associated with post-grant validations in countries that require a full translation of the specification. This makes sense with a 200+ page description, but similar considerations are rarely found in the mechanical and electrical fields, where a lighter touch approach is typical.

In an attempt to harmonize description amendment practice, the 2021 updated guidelines for examination introduced some significant changes. In particular, the 2021 guidelines indicated that embodiments in the description that are not covered by the allowed claims must be deleted or explicitly marked as "not claimed."

The guidelines also indicated that claim-like clauses — also known as numbered embodiments — should be deleted, as they allegedly result in confusion with the scope of the claims. The biggest impact for applicants, however, was that the revised guidelines indicated that applicants should be summoned to oral proceedings should they not amend the description as requested.

While the practice of description amendments had been questioned from time to time, following the updated guidelines in 2021, the body of case law from the EPO's boards appeal started to grow. The key question raised in this case law is whether there is legal basis for requiring description amendments. The issue was also touched on in the recent decision of the Enlarged Board in G 1/24, in June, which concluded that the description and drawings shall always be consulted to interpret the claims.¹

Since G 1/24 looked at the relationship between the claims and description for the question of claim interpretation, many practitioners hoped that G 1/24 might also clarify the legal basis for description amendments. Unfortunately, that was not the case, but it is notable that the referral in G 1/25 has arisen mere weeks after the G 1/24 decision was issued. This seems to suggest that it was not only EPO attorneys looking for clarification on this point, but also the Boards of Appeal.²

The Referring Case

The referring case, T 697/2, is an appeal by both the patentee, Knauf Insulation, and the opponent, Rockwool International A/S, against the opposition division's decision to maintain European patent EP2124521 on the basis of an auxiliary request, i.e., claims in amended form.

The patent itself relates to a method for growing a plant in a hydroponics growing medium comprising mineral fibres and an organic binder. The claims of the auxiliary request specified, among other features, that the binder was "based on reaction products obtained by curing an aqueous solution comprising citric acid, ammonia and dextrose."³

The auxiliary request also included an amended description. However, the opponent was of the view that this description was inconsistent with the amended claims. Specifically, the opponent highlighted that the definition of the binder given in the amended description was broader than that defined by the claims, with the components of citric acid, ammonia and dextrose being indicated as optional.

The opponent argued that this inconsistency introduced a lack of clarity. The opposition division disagreed, finding that any alleged inconsistency was present in the patent as granted, and therefore could not be examined as part of the opposition — at the EPO, a lack of clarity is not a ground of opposition unless introduced by amendments during the opposition. The opposition division therefore found the auxiliary request to be allowable.

The Referring Decision

Both parties filed an appeal against the decision of the opposition division, with grounds of appeal being filed in June 2022. Board 3.2.04 was initially assigned the case and oral proceedings were scheduled for March 18, 2024.

However, the oral proceedings were canceled and the case transferred to Board 3.3.02, due to technical aspects of the appeal. This is rather unusual. Oral proceedings were rescheduled for Dec. 19, 2024, and in March 2025 the board issued a communication indicating that a referral to the Enlarged Board appeared necessary, inviting the parties to comment.

The board ultimately agreed that the subject matter of the auxiliary request was novel, inventive and sufficiently disclosed, but disagreed with the opposition division's conclusion that clarity was not an issue.

According to the board of appeal, the additional features relating to the binder had only been optional in the patent as granted, but were made mandatory in Claim 1 of the auxiliary request — see Part 10.2 of the referring decision. Thus, in line with the principles of G 3/14, the board concluded that the claims of the auxiliary request could be assessed for clarity.

As previously noted, the opponent highlighted that the amended description of the auxiliary request included a broader definition of the binder than defined in the claims. The board agreed that there was an inconsistency in this definition, and therefore concluded that the allowability of the claims turned on whether this inconsistency between the claims and description was in contravention of the European Patent Convention, or EPC.

For a decision to be referred to the Enlarged Board, it is necessary for a board of appeal to show that there is a divergence in European case law that must be resolved. There is not a specific rule or article of the EPC that explicitly requires description amendments. The referring board identified two diverging strands in the existing case law regarding the existence, or lack, of legal basis for requiring description amendments.

The first strand of case law finds that there is legal basis for mandating description amendments in the EPC, even if this is not expressly tied to a single provision. These decisions frequently cite Article 84 of the EPC — clarity, either alone or in combination with other parts of the EPC, such as Rule 42 of the EPC — content of the description, and/or "general legal principles."⁴This latter point is somewhat vague, but seems to be the origin of the legal certainty for third parties stance of Article 69.

The second strand of case law finds that there is no legal basis for refusal of an application if there is an inconsistency between the claims and description. This case law is less well established, starting with T 1989/18),⁵and only relates to appeals from examination proceedings.

These boards of appeal were of the view that the clarity of the claims is not affected if the description contains subject matter that is not claimed. One interesting point raised in this strand of case law is that in the travaux préparatoires — the minutes of the meetings that led to the EPC — there was general acceptance that a patent application should not be refused, even if it contained statements or subject matter contrary to "ordre public" or morality.

As such, it was argued that it could not have been the intent of the drafters of the EPC to refuse applications for less severe reasons, such as a lack of clarity resulting from inconsistencies between the claims and description.

In view of the above, the board of appeal in T 697/22 referred three questions to the Enlarged Board, as follows.

1. If the claims of a European patent are amended during opposition proceedings or opposition-appeal proceedings, and the amendment introduces an inconsistency between the amended claims and the description of the patent, is it necessary, in order to comply with the requirements of the EPC, to adapt the description to the amended claims, so as to remove the inconsistency?
2. If the first question is answered in the affirmative, which requirement(s) of the EPC necessitate(s) such an adaptation?
3. Would the answer to questions 1 and 2 be different if the claims of a European patent application are amended during examination proceedings or examination-appeal proceedings, and the amendment introduces an inconsistency between the amended claims and the description of the patent application?⁶

Practice Points

In the past, it has been possible for applicants to request a stay of proceedings pending the outcome of a referral to the Enlarged Board. More recently, however, the EPO president has closed off this option, presumably to avoid adding to the existing backlog of cases at the EPO, and the G 1/25 referral is no exception.

Consequently, the EPO will continue examination and opposition proceedings while referral G 1/25 is pending. However, while we await the outcome of the referral, the extent of description amendments that will be required will depend on the specific examiner handling the application.

Some examiners may continue to take the hard-line approach currently set out in the guidelines, particularly as the examining divisions are bound to follow the guidelines, but others may be more flexible in light of the pending referral. It may therefore be productive to open a dialogue with the examiner, particularly where extensive description amendments may be required if a strict approach is taken.

It is worth noting that the Enlarged Board may reword the questions or choose not to answer them. Even if the Enlarged Board does answer the questions directly as referred to them, differences in approach are likely to remain if description amendments are found to be required, as there are many ways to both draft and then subsequently amend an application.

If the Enlarged Board cannot find a legal basis for the practice of description amendments, it will be a significant shift for the EPO, and a move away from practice at many national European patent offices that also require description amendments. It would, however, harmonize the EPO's prosecution process with those of other IP5 countries, consisting of the U.S., Japan, South Korea, China and the EU, which do not require description amendments.

Since G 1/24 sought a move toward global harmony when considering claim construction, could we see the same here, or was G 1/24 simply a one-off?

Footnotes

1. https://link.epo.org/web/case-law-appeals/Communications/G_1_24_Decision_of_the_Enlarged_Board_of_Appeal_of_18_June_2025.pdf.

2. https://www.epo.org/en/case-law-appeals/communications/referral-enlarged-board-appeal.

3. https://www.epo.org/en/boards-of-appeal/decisions/t220697ex1

4. Points 14.3.1 to 14.3.5 of the referring decision.

5. https://www.epo.org/en/boards-of-appeal/decisions/t181989eu1.

6. https://link.epo.org/web/press-release/2025/en-datasheet-interlocutory-decision-t-697-22.pdf.

Originally published by Law360.

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