UPC vs EPO: Key Procedural Differences In Challenges To Patent Validity

A notorious aspect of proceedings at the UPC is their frontloaded nature, according to which parties are required to set out their full case as early as possible. This is to assist with meeting the strict timelines for judgments; the UPC aims to issue a first-instance decision within one year of the filing of a complaint. Another notable aspect of UPC proceedings is that patentees are permitted to defend their patent against validity attacks by way of only a "reasonable number" of auxiliary requests (ARs), again to facilitate procedural economy.

Now that the UPC has been operational for over two years, a body of case law has emerged, demonstrating how strictly the frontloading principle is applied in practice and how restricted patentees may be when seeking to pursue auxiliary requests. It is helpful to compare the level of procedural flexibility at the UPC with that in EPO oppositions, as this may have strategic implications.

Frontloading requirements at the UPC

The obligation on parties comprehensively to prepare their case at the outset is enshrined by Rule 9.2 of the UPC's Rules of Procedure (RoP), which provides that "The Court may disregard any step, fact, evidence or argument which a party has not taken or submitted in accordance with a time limit...". Rule 263 RoP further provides that leave for amendment to a case may only be granted if (a) the amendment could not have been made with reasonable diligence at an earlier stage, and (b) the amendment will not unreasonably hinder the other party in conduct of its action. It was thus expected that the UPC would be very strict procedurally and exercise discretion restrictively regarding amendments to a case, and this approach has been borne out in its case law to date.

In particular, it appears that late-filed prior art will generally be inadmissible, unless perhaps it is truly obscure or relates to a prior use, such that a party could not previously have known of its existence. The order issued in UPC_CFI_597/2024 provides an illustration of the court's approach. The Milan Central Division excluded a US patent publication first mentioned by the claimant for revocation in their reply to the proprietor's defence as being inadmissible because it could have been filed at an earlier stage. The court referred to a general principle of diligence and suggested that submission of a document at a later stage could only be justified if it was not previously available or could not have been submitted earlier.

A similar approach was followed in an order issued in UPC_CFI_745/2024 in an infringement action before the Mannheim Local Division. A new prior art document filed by the counterclaimant for revocation two months after their counterclaim for revocation was again excluded. The counterclaimant argued that they had only recently become aware of the document despite a diligent prior art search previously having been carried out, and also that the proprietor would not be prejudiced, given the new prior art was their own previous patent application. Nonetheless, the court held that an oversight in a prior art search did not justify the introduction of new prior art.

Late filing considerations are also applicable to new lines of argument. Thus, in UPC_CFI_26/2024, a new line of argument for added matter raised at the oral hearing was rejected. The Düsseldorf Local Division noted that, although an issue of added matter had been raised from the outset, the new argument was based on completely different passages of a lengthy document and neither the court nor the other party should be forced to deal with it from scratch. Similarly, in UPC_CFI_459/2023, new prior art attacks made at the oral hearing from existing documents were not admitted. The Düsseldorf Local Division stated in this regard that strategic tactics aimed at surprise are alien to the RoP.

A more generous approach may, though, be applied when considering new expert evidence and argumentation in the written procedure, which clearly responds to arguments made by the other party, to ensure fairness in proceedings. In a decision issued in UPC_CFI_312/2023, a new declaration filed by the claimant with its reply to the Defence was admitted because it responded to arguments newly made by the defendant regarding common general knowledge. A similar approach was taken by the Paris Central Division in UPC_CFI_307/2023, which admitted new evidence (a declaration and documents referenced therein) disputing facts alleged by the defendant, on the basis of responsiveness to new facts and arguments raised in the defence. Relatedly, in UPC_CFI_1/2023, expert evidence filed by the claimant after the defendant's rejoinder to address new points arising from the defendant's expert declarations was admitted in view of the specific circumstances of the case, and because the evidence was concise and addressed a small number of discrete points.

In summary, a review of the UPC's procedural orders confirms that significant restrictions apply to changes to a party's case on validity, in particular prior art relied on, but also lines of argument. Parties should thus present their complete case at the outset and be mindful that later changes may well be inadmissible.

Comparison with the EPO

While the EPO may also disregard facts or evidence that are not submitted in due time by parties (Article 114(2) EPC), the EPO's admissibility regime is more permissive than that of the UPC, at least in first instance opposition proceedings. In particular, a criterion of prima facie relevance is a key consideration when assessing admissibility of late-filed facts and evidence at first instance. Thus, although principles of procedural economy also apply at the EPO, a highly relevant document is unlikely to be excluded even if it is filed at a later stage in first instance opposition proceedings. In contrast, high relevance does not appear to be able to compensate for late filing at the UPC.

Another key distinction compared to the UPC is that the first instance Opposition Division (OD) of the EPO issues a preliminary opinion on validity during the written procedure. Issues raised in the OD's preliminary opinion can subsequently be cited as a basis for justifying filing of new facts and evidence. At the UPC, no such preliminary opinion is issued, with an interim conference instead dealing with case management issues.

The OD also set a final deadline (Rule 116(1) EPC) ahead of oral proceedings for filing written submissions, including new facts and evidence, with new facts and evidence presented after that date needing not to be considered unless the subject of the proceedings has changed. The EPO's Rules thus specifically contemplate filing of new facts and evidence at a later stage, in contrast to the UPC. In practice, there are also much more limited restrictions regarding pursuing new lines of argument at first instance in the EPO, with parties commonly being able to present new technical arguments at oral proceedings.

In general, parties thus have more flexibility to develop their case on validity during first instance opposition proceedings at the EPO compared to the UPC. While it remains highly recommended to present a complete case initially, a highly relevant document identified at a later stage is still likely to be able to be introduced into first instance proceedings.

The EPO's procedural rules on appeal (Rules of Procedure of the Boards of Appeal, RPBA) are, however, much more in line with the UPC's practice. A party's initial appeal brief should contain their full case, which should be directed to the requests, facts, objections, arguments and evidence on which the first instance decision was based, with amendments only admitted at the Board's discretion (Articles 12(2), (4) RPBA). Subsequent amendments to a party's appeal case need to be justified and are again subject to the Board's discretion, with further, more stringent criteria applying at later stages in the appeal (Articles 13(1), (2) RPBA). Thus, parties need to be mindful of the strict procedural constraints on appeal at the EPO, and ideally need to have their complete case on file by the end of the first instance proceedings.

Auxiliary Requests at the UPC

In common with the EPO, the UPC allows patentees to defend validity of their patent by way of a series of conditional auxiliary claim requests with amended claim wording, to be considered in order of preference if a main request (e.g. the claims as granted) fails for invalidity. An important point of distinction, though, is that the UPC's RoP impose a requirement that auxiliary requests be "reasonable in number in the circumstances of the case" (Rule 30.1(c) RoP). Given this rather open definition, and the restrictions imposed by frontloading requirements on changes to auxiliary request strategy at a later stage, it has been of particular interest to see how the UPC has assessed auxiliary requests filed by patentees in its case-law to date.

General guidance on factors to be considered in assessing if a number of ARs is "reasonable" has been provided in various cases, including UPC_CFI_255/2023, UPC_CFI_298/2023, UPC_CFI_15/2023, and UPC_CFI_526/2024. Complexity of the case, importance of the patent(s), and interrelationship with other proceedings should be considered. While there is no general rule requiring convergence (that all ARs progress in the same direction), the presentation and structure of the auxiliary requests is relevant – preparation of the court and the other party must not be made unreasonably difficult by the number of ARs and the way of their presentation (UPC_CFI_526/2024).

In terms of concrete numerical limits on ARs, this has been assessed on a case-by-case basis. Thus, in UPC_CFI_255/2023, 84 ARs were considered to be an admissible number due to "extreme complexity" and the various grounds of invalidity raised, but the court noted that this number is "extremely high". In contrast, in UPC_CFI_526/2024, 80 ARs (40 x 2 alternative forms) were held to be excessive based on limited complexity of the technology, excessive combinations of features and lack of structure. The existence of multiple ongoing related proceedings was not considered to justify the high number of ARs, since the court held that these more advanced proceedings should instead have assisted in narrowing the ARs to the most relevant issues. The patentee was however permitted to limit and/or reorder their ARs, with up to 10 being viewed as reasonable in the circumstances.

In UPC_CFI_298/2023, 55 ARs were considered not unreasonable (after panel review of an order of the Judge Rapporteur to limit to a single digit number), while the exact number that might ultimately be reasonable was to be reassessed at a later stage. (In a later order in the same case, a total of 4 ARs was considered indisputedly reasonable in number.) 21 ARs were considered reasonable in UPC_CFI_380/2023, and 12 ARs (instead of 65) were considered the upper limit of reasonable in UPC_CFI_316/2023.

While it is difficult to draw any firm conclusions on what will generally be considered a reasonable number of ARs based on the variation between cases (also in the absence of guidance from the UPC Court of Appeal), the case law does at least provide some useful precedent that can be considered when developing an AR strategy. It seems also that a single digit number of ARs (assuming justified based on grounds of challenge) are unlikely to be viewed as excessive, with more uncertainty when pursuing larger numbers.

Turning to other considerations relating to ARs at the UPC, an application to amend requires some explanation of how ARs meet formal requirements and are valid/infringed (if applicable) (Rule 30.1(b) RoP). The extent of explanation required is unclear, but the Paris Central Division commented in their decision in UPC_CFI_255/2023 that an insufficient explanation could be addressed at a later stage.

As regards pursuing new amendments after an initial application to amend, the same late-filing considerations discussed above are applicable. Thus, in an order issued in UPC_CFI_210/2023, the court made general statements regarding considerations for admissibility of new amendments. In particular, arguments already made by the claimant for revocation should be factored in when assessing admissibility of a new amendment, i.e. it should be considered whether the amendment would have been necessary at an earlier stage. Whether the late request for amendment will cause a delay in proceedings should also be considered.

Finally, one area where there has been some divergence is the admissibility of new ARs where these are being pursued in a parallel EPO case. In UPC_CFI_310/2023, new ARs taken from parallel EPO proceedings were not admitted in the UPC proceedings, as the patentee had initially pursued a different defence strategy, and had not indicated an intention to coordinate strategy with the EPO proceedings. In UPC_CFI_316/2023, new ARs filed after a decision of the EPO in a parallel case that had cast doubt on clarity were not admitted by the court, since a clarity objection had already been raised and should have been considered previously. In UPC_CFI_425/2024, new ARs based on claims upheld by the OD were in contrast admitted, with the court citing the principle of synchronising UPC and EPO proceedings underlying R295(a) RoP.

Comparison with the EPO

The EPO does not impose any numerical requirement on ARs that can be filed in an opposition defence, and thus patentees have more flexibility in defending validity at the EPO by way of ARs compared to the UPC. As discussed above, late filing considerations are also less pronounced at the EPO at first instance, and a strategy of filing a few initial ARs and then filing a more comprehensive set of ARs at a later stage (by the Rule 116(1) EPC deadline), taking into account the OD's preliminary opinion, can be taken. It can also be permissible to file a new AR even as late as at first instance oral proceedings, in particular where the OD has made a divergent finding on validity compared to their initial preliminary opinion. Accordingly, differences in AR strategy and timing may well arise between an EPO opposition and a revocation defence at the UPC.

On appeal, the position is as discussed above and more in line with the UPC's practice, in that all ARs should be set out in the patentee's initial appeal brief, ideally also having been on file by the end of first instance proceedings.

Conclusion

The clear lesson from the UPC's procedural case law to date is that frontloading requirements are being strictly applied, and it is very challenging to make amendments to a case. Claimants should therefore have carefully prepared their complete case before filing. Given the very tight deadline at the UPC for defence of validity (two months from the statement for revocation for filing of a statement of defence and application to amend), the frontloading requirement, and the requirement for the number of ARs to be reasonable, there is significant pressure on a defendant in a revocation action.

In contrast, the EPO's first instance opposition procedure has greater procedural flexibility, and it is possible to develop one's case at a later stage, including by way of additional ARs, with no strict limit on the number of ARs that can be pursued. Parties should though be aware that procedural restrictions are much more severe on appeal, in line with the UPC's practice, and look to have their complete case on file at least by the end of first instance proceedings.

For patents that have not been opted out from the UPC, and are still in their opposition period at the EPO (nine months from the date of grant), both systems for challenge (UPC revocation and EPO opposition) are available. The respective merits of revocation proceedings at the UPC and opposition proceedings at the EPO, including based on their differences in procedure, should be carefully considered.

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