3. Materiellrechtliche Prüfung der Beschwerde

In T 644/24 hatte die Kammer zu prüfen, ob die von der Beschwerdeführerin erstmals im Beschwerdeverfahren erhobenen Einwände unzureichender Offenbarung und unzulässiger Erweiterung als neue Einspruchsgründe im Sinne von G 10/91, Nr. 3 des Tenors anzusehen waren.

Die Kammer erinnerte eingangs daran, dass im Beschwerdeverfahren neue Einspruchsgründe nur mit dem Einverständnis des Patentinhabers geprüft werden dürfen (G 10/91, Nr. 3 des Tenors). Zugleich sind Änderungen der Ansprüche oder anderer Teile eines Patents, die im Einspruchs- oder Beschwerdeverfahren vorgenommen werden, im Beschwerdeverfahren in vollem Umfang auf die Erfüllung der Erfordernisse des EPÜ wie z. B. des Art. 123 (2) EPÜ überprüfbar (G 10/91, Nr. 19 der Gründe). Die Kammer schlussfolgerte, dass Art. 100 c) EPÜ im Beschwerdeverfahren daher nicht angewendet und das Patent wie erteilt nicht auf eine unzulässige Erweiterung geprüft werden darf, wenn der Einspruchsgrund nach Art. 100 c) EPÜ im Einspruchsverfahren nicht erhoben wurde und der Patentinhaber der Prüfung nicht zustimmt. Änderungen des Patents im Einspruchs- und Beschwerdeverfahren können im Beschwerdeverfahren unter Anwendung von Art. 123 (2) EPÜ hingegen auch ohne Zustimmung des Patentinhabers bezüglich des Vorliegens einer unzulässigen Erweiterung geprüft werden.

Des Weiteren stellte die Kammer fest, dass in G 10/91 nicht erörtert wird, ob ein geänderter Patentanspruch im Einspruchs- oder Beschwerdeverfahren nach Art. 123 (2) EPÜ zur Gänze bezüglich einer unzulässigen Erweiterung geprüft werden darf oder nur bezüglich unzulässiger Erweiterungen, die von der Änderung herbeigeführt wurden. Nach Ansicht der Kammer ist Letzteres der Fall. Zum Einen spricht G 10/91, Nr. 19 der Gründe, nicht von "geänderten Ansprüchen", sondern von "Änderungen der Ansprüche", die auf die Erfüllung des Erfordernisses von Art. 123 (2) EPÜ zu prüfen sind. Zum Anderen greift das in G 10/91, Nr. 18 der Gründe genannte Verbot der Einführung neuer Einspruchsgründe im Beschwerdeverfahren ohne Zustimmung des Patentinhabers.

Ähnliche Überlegungen gelten für den Einspruchsgrund nach Art. 100 b) EPÜ, der nach Ansicht der Kammer als eigenständige materiellrechtliche Norm für das Erfordernis der ausreichenden Offenbarung bzw. der Ausführbarkeit bezüglich des Patents wie erteilt anzusehen ist. Unter Berücksichtigung des für das gesamte Patentsystem grundlegenden Zwecks von Art. 83 EPÜ muss in teleologischer Hinsicht davon ausgegangen werden, dass das Erfordernis der ausreichenden Offenbarung auch für das geänderte Patent gelten muss. Die Große Beschwerdekammer stellte dies im Rahmen von G 3/14, Nr. 77 fest, wo Art. 83 EPÜ unter den Erfordernissen des EPÜ genannt wird, "die eindeutig unter Art. 101 (3) EPÜ fallen". In Nr. 76 der Gründe stellte sie unter Verweis auf G 10/91 zudem klar, dass ein Einwand nicht ausreichender Offenbarung im Beschwerdeverfahren ohne Einverständnis des Patentinhabers nur im Hinblick auf die Änderung im engeren Sinn, nicht aber im Hinblick auf "das gesamte Patent [...] oder [...] den [gesamten] geänderten Anspruch" geprüft werden darf. Der Kammer zufolge entspricht diese Überlegung auch der Kernaussage zur Auslegung von Art. 101 (3) EPÜ und Art. 84 EPÜ in G 3/14. Die Zusammenschau von Tenor und Nr. 76 der Gründe zeige auf, dass die Große Beschwerdekammer den Umstand, dass Art. 84 EPÜ kein Einspruchsgrund ist und den Umstand, dass ein zuvor nicht erhobener Einspruchsgrund nach Art. 100 b) EPÜ gemäß G 10/91 im Beschwerdeverfahren ohne Einverständnis des Patentinhabers nicht geprüft werden darf, für das Beschwerdeverfahren im Ergebnis gleichgesetzt hat. Die Kammer befand daher, dass das Ausmaß der Prüfungsbefugnis bezüglich unzureichender Offenbarung beim geänderten Patent dem Ausmaß bezüglich unzulässiger Erweiterung entspricht. Wurden die Einspruchsgründe nach Art. 100 b) und c) EPÜ im Einspruchsverfahren nicht erhoben und erteilt der Patentinhaber nicht sein Einverständnis zu deren Prüfung, darf der Kammer zufolge im Beschwerdeverfahren das Patent im Fall einer Änderung im Einspruchs- oder Beschwerdeverfahren daher nicht in seiner Gesamtheit, sondern nur insoweit auf unzureichende Offenbarung und unzulässige Erweiterung geprüft werden, als die Änderung diese herbeiführt.

Im Übrigen hob die Kammer hervor, dass im Einspruchsverfahren zu berücksichtigen ist, dass die Einspruchsabteilung die Möglichkeit hat, ausnahmsweise auch neue Einspruchsgründe in das Einspruchsverfahren einzuführen. Da dies bereits für das Patent wie erteilt gilt, ist die Einspruchsabteilung in Anwendung des Art. 114 (1) EPÜ nicht darin gehindert, das geänderte Patent in seiner Gesamtheit zu prüfen.

In T 246/23 of 11 March 2026 the board rejected the objection under Art. 24(3) EPC and refused the opponent's request for cost apportionment.

During the oral proceedings in T 246/23 of 7 August 2025, when the debate on auxiliary request 5 was opened, the board in its original composition (the "original board") had informed the parties of its preliminary view that the request contravened the principle of no reformatio in peius. The patent proprietor (respondent) had then raised an objection of suspected partiality against all board members, arguing that an objection based on this principle could only be raised by another party, not by the board. It submitted that, since the board had raised the objection ex officio, it was "on the side" of the opponent (appellant) and thus suspected to be partial. The original board had found the objection admissible and the composition of the board was changed for the purposes of a decision on the objection under Art. 24(3) EPC (the board in its new composition in the following referred to as "the board").

The board noted that, on the substance of the objection, the respondent relied on two core arguments, neither of which was convincing: (1) that the specific nature of the prohibition of reformatio in peius prevented the board from raising it ex officio, and (2) that established case law supported this view.

On (1), the board stated that the prohibition of reformatio in peius is not so exceptional as to completely escape the board's powers under Art. 114 EPC. It noted that any objection raised by the board ex officio in an inter-partes procedure can be perceived as being in a certain contradiction with the board's obligation to remain neutral towards the parties. However, if the parties were free to raise the objection of suspicion of partiality in all cases where a board exercises its powers under Art. 114 EPC, such powers would be effectively eliminated. The board also rejected the argument that raising the prohibition ex officio contradicts the principle of party disposition. This principle concerned the substantive outcome of proceedings, i.e. the scope of the legal effects sought, and did not extend to the legal arguments raised by either the parties or the court for achieving the requested legal effects. In the present case, the opponent requested the revocation of the patent, and the original board's finding that auxiliary request 5 was not allowable, for whatever reason, was clearly within the scope of the appellant's appeal request for revocation.

On (2), the board pointed out that there was no settled case law forbidding the board from raising the objection ex officio. It added that this could not even be derived from cited decision T 1544/07. In its view, T 1544/07 only found that the deciding board had no obligation to raise the objection under the special circumstances of that case, where the opponent itself had explicitly waived the right to raise it. The decision did not state that a board is prevented from raising the objection ex officio as a question of principle. Rather, it appeared to suggest that a board may, but need not, raise it where the affected party renounces this defence. A far stricter position was taken in T 882/17, cited by the opponent, where the deciding board disagreed with T 1544/07 and unambiguously stated that the board not just may, but must take the prohibition into account, and also ex officio. This decision was followed by other decisions (T 1773/22, T 1472/21).

The board explained that, to decide the issue before it (i.e. the objection of suspected partiality) it was sufficient to establish that, contrary to the proprietor's argument, case law was far from settled. The mere existence of another line of case law, T 882/17, recognising the board's entitlement to raise the prohibition objection, was sufficient to establish that the original board could not be considered partial solely for raising the objection. According to the board, a board of appeal is always entitled and in fact obliged to examine the boundaries of its own powers to raise an ex officio objection. If necessary, it is also entitled to question findings of previous decisions on the same issue. The original board was under no obligation to seek the proprietor's permission or to maintain the objection only contingent on the opponent's intention to pursue it.

The board concluded that the objection under Art. 24(3) EPC was unsubstantiated. It also refused the opponent's request for cost apportionment, noting that it could not qualify the procedural conduct of the proprietor as an abuse of procedure.

In T 989/23 auxiliary request 17, filed with the statement of grounds of appeal, had first been filed in the opposition proceedings on the final date set under R. 116 EPC. The opposition division had decided that this auxiliary request was not open for examination as to its admissibility since it had been filed within the set time limit. Auxiliary request 17 was not considered by the opposition division since a higher-ranking auxiliary request was found allowable. The appellant-opponent requested that auxiliary request 17 not be admitted into the appeal proceedings, arguing that the division had misunderstood its discretionary powers.

In view of the line of case law holding that submissions admitted by the opposition division could not be excluded from consideration on appeal (e.g. T 487/16, T 1768/17, T 617/16, T 26/13, T 989/23, T 1568/12, T 2603/18, T 3201/19) the board first addressed the extent of its power of review. It explained that like an opposition division's decision to disregard late-filed submissions, a decision to admit such submissions into the opposition proceedings was a discretionary procedural decision which formed part of the opposition division's final decision on the merits of an opposition. A decision to admit late-filed submissions adversely affected the party contesting their admittance (in view of a possible adverse decision on appeal based on the admitted submissions, T 1549/07). Therefore, a board had the power to review an opposition division's procedural decision to take into consideration submissions filed late in opposition proceedings. Otherwise, the parties' right to a judicial review of an essential part of the opposition division's decision would be denied. Moreover, on appeal, a board would be compelled to accept a legal and factual framework, even if it is based on an erroneous exercise of discretion. As a consequence, requests, facts or evidence that had been admitted into opposition proceedings could be disregarded on appeal if the opposition division's decision suffered from an error in the use of discretion (T 1209/05, T 1652/08, T 1852/11, T 2197/11, T 572/14, T 341/15, T 326/22, T 776/17). The board thus had the power and duty to review the opposition division's decision to admit auxiliary request 17 into the opposition proceedings.

The board held that the filing of requests for amendment of the patent was governed by Art. 123(1) EPC, which gave the opposition division the discretionary power not to admit new requests for amendment (e.g. T 755/96, OJ 2000, 174; T 980/08, T 1178/08, T 966/17, R 6/19, T 256/19, R 11/20). The exercise of this discretion had to take account of the following: In inter-partes proceedings, each party had to be given equal opportunity to present their case and a fair chance to respond to new matter raised by the other party or parties or by the opposition division. Both the opposition division and the parties had to observe the principle of good faith (T 669/90, OJ 1992, 739; T 201/92). To expedite the proceedings and implement the principle of fairness towards the other party or parties, each party had to submit all facts, evidence, arguments and requests for amendments relevant to their case as early and completely as possible (T 326/87, OJ 1992, 522; T 430/89; T 951/91, OJ 1995, 202). This case law had been developed mainly in the context of Art. 114(2) EPC, pertaining to facts and evidence. Nevertheless, in view of the principles set out above, the rationale of this case law also applied to a patent proprietor's requests for amendment of the patent (e.g. T 582/08). Whether amended sets of claims should be considered in opposition proceedings or not did not merely depend on their filing within the time limit under R. 116 EPC, but also on the specific circumstances of the case (see also T 364/20). Consequently, the opposition division erred in denying that it had discretionary power to disregard auxiliary request 17. As a consequence, this procedural decision did not establish that auxiliary request 17 was "admissibly raised" in opposition proceedings.

The board agreed with the opponent that the filing of additional sets of amended claims (including auxiliary request 17) on 23 January 2023 was not a diligent and appropriate reaction to the opponent's submissions filed on 14 April 2022 and reiterated on 2 September 2022, or to the opposition division's communication of 30 May 2022. Since part of the defences submitted by the proprietor was not able to overcome the board’s conclusions on lack of inventive step and a later filed part raised new issues, the board did not admit auxiliary request 17 into the appeal proceedings.