Towards a uniform test of equivalence before the UPC

This article analyses the UPC’s early decisions by:

1. identifying emerging trends in the application of the DoE, and

2. reflecting on the Court’s guidance concerning incidental questions, namely the applicable law and amendments to the case. 

    

From national tests to a common functional threshold

To date, six Local Divisions (Brussels, Düsseldorf, Hamburg, Mannheim, Paris and The Hague) have ruled on the DoE. As the UPC Agreement does not include any explicit provision on the DoE, the Local Divisions have been required to determine which test to apply in order to assess the cases brought before them.

The Dutch four-step test

The choice was straightforward for the Local Division of The Hague, in both Plant‑e v. Arkyne Technologies (UPC_CFI_239/2023, 22 November 2024) and Washtower v. BEGA (UPC_CFI_479/2025, 11 September 2025), since the parties had agreed to rely on the Dutch DoE doctrine. This doctrine, first articulated,  in the Eli Lilly v Fresenius decision by the Hague Court of Appeal (2020),entails answering the following four questions:

1. Technical equivalence: does the variation solve (essentially) the same problem that the patented invention solves and perform the same function?
2. Fair protection to the patentee: is extending the protection of the claim to the equivalent proportionate to a fair protection for the patentee, in view of his contribution to the art and is it obvious to the skilled person from the patent publication how to apply the equivalent element (at the time of infringement)?
3. Reasonable legal certainty for third parties: does the skilled person understand from the patent that the scope of the invention is broader than what is claimed literally?
4. Is the attacked embodiment novel and inventive over the prior art? This requirement is not met if the alleged infringer can successfully assert a Formstein or Gillette defence.

In Plant‑e v. Arkyne Technologies, the Local Division of The Hague additionally justified the application of this national test on the ground that it reflects a synthesis of DoE principles recognised in multiple European jurisdictions. In Washtower v. BEGA (UPC_CFI_479/2025), it further emphasised the desirability of a harmonised UPC standard, pending clarification by the UPC Court of Appeal.

The emerging UPC common “functional threshold” standard

In the other cases concerning DoE, the parties could not agree on the test to apply, so the Brussels, Düsseldorf, Hamburg, Mannheim and Paris Local Divisions had to choose one. This enabled them to adopt a lowest common denominator approach, resulting from the US “function-way-result” test that is applied in multiple European jurisdictions, either directly (sometimes even codified in the law itself) or in modified/comparable forms. For the function-way-result-Test, three questions are to be assessed:

• Does the accused product perform substantially the same function? (“function”);
• Does it do so in substantially same way? (“way”);
• Does the accused product obtain the same result? (“result”).

The decisions by the Local Divisions did not specify any DoE requirements beyond the three requirements of the function-way-result test, as infringement by equivalence was already rejected based on the three questions of the function-way-result test alone.

The first UPC decision to address DoE was Ballinno v. UEFA (Hamburg LD, UPC_CFI_151/2024, 3 June 2024), ruling on provisional measures. The Local Division held that equivalence cannot be reduced to a mere comparison of effects, understood in the context as the immaterial advantage provided by the means or result. The Court observed that the decisive question is how that technical effect is achieved. As the alleged variant relied on acceleration sensors rather than acoustic sensing as required for the patented connected ball, the Court concluded that functional equivalence was absent. A key factor in this assessment was that the patent description envisaged acceleration sensors as an additional means operating alongside the acoustic sensors, rather than as an alternative means.

In OrthoApnea v. M. (Brussels LD,UPC_CFI_376/2023, 17 January 2025), the Court applied both the function‑way‑result and insubstantial‑differences tests (a different test also applied in the US) but emphasised that technical-functional equivalence operates as a threshold requirement. The Court found that this threshold had not been met due to differences in the way the patented and accused means performed the function. The Court also noted that prosecution amendments that limited the scope of the claims restricted the range of permissible equivalents.

The requirement for the UPC to develop a unified DoE and end national fragmentation is clearly stated in Dish v. Aylo (Mannheim LD, 6 June 2025, UPC_CFI_471/2023). The Court observed that divergences among Member States’ national doctrines stemmed from the former absence of a central judicial authority. With express reference to the Brussels LD decision, the Court confirmed that functional equivalence constitutes the threshold condition. The Court indicated that the DoE is rejected if “the modified means do not fulfil essentially the same function, in order to achieve the same effect ”, while also indicating that “if the same function is not used as a basis, at least essentially the same effect is used as a basis”. We note that the court uses the term “effect” (“Wirkung” in the German original), rather than “result” (as in the AIPPI Q175 final resolution, in the sense of the immaterial advantage provided by the means). We assume that the meaning of those terms are the same. To avoid any confusion with the “primary technical effect”, i.e. the function, a decision of the Court of Appeal on the terms to be used and their definitions would be welcome. 

The same reasoning line was followed in N.J Diffusion v. Gisela Mayer (Paris LD, 1^st August 2025, UPC_CFI_363/2024). The Court explicitly designated the function-way-result test as the “lowest common denominator”, aligning itself with the methods of the Mannheim and Brussels divisions. Citing Dish v. Aylo, N.J Diffusion v. Gisela Mayer, OrthoApnea, Washtower v. Wasombouw, the Court reiterated the same guiding principle in Hartmann Packaging v. Omni-Pac (Dusseldorf LD, 15 October 2025, UPC_CFI_115_2025_and_377_2024).

Pragmatic approach on applicable law and amendment to the case

Application of the DoE has also led to issues in relation to applicable law. In Dish v. Aylo, the LD Mannheim applied to DoE the principle clarified in a previous decision of LD Munich (11 March 2025, UPC_CFI_162/2024) which may be already familiar to the interested reader from one of our earlier publications (see link), namely that acts:

• committed after 1 June 2023 fall under the UPCA;
• committed (and concluded) before that date are governed by national law;
• began before and continuing after the entry into force of the UPCA are governed by the UPCA.

The LD Mannheim specified that, where national law applies, the UPC should apply the national doctrine of equivalence in the same way as a purely national court of that Member State would.

Raising arguments on DoE has also clashed with the front-loaded principle of UPC proceedings. The application of this principle requires that the claimant sets out all factual and legal arguments (“the facts relied on”, “the evidence relied on”, and “the reasons why the facts relied on constitute an infringement of the patent claims, including arguments of law”) in the Statement of Claim (Rule 13 RoP). But in practise, arguments on DoE usually come into play when responding to the defendant’s statement of defence. This issue came up in a few cases. The Court of Appeal clarified in OrthoApnea (21 November 2024, UPC_CoA_456/2024) that introducing an equivalence argument does not alter the nature of the dispute and thus does not constitute an amendment requiring leave under Rule 263 RoP. This liberal interpretation was subsequently confirmed in Wonderland v. Cy (14 October 2025, Düsseldorf LD, UPC_CFI_807_2024 and UPC_CFI_334_2025), and the abovementioned cases AIM Sport v. Supponor, TGI v. AIM Sport, DISH v. AYLO, N.J Diffusion v. Gisela Mayer. 

However, the above-mentioned decision in Hartmann Packaging v. Omni-Pac shows that there are limits even to the liberal approach, ruling that the claimant’s arguments on equivalence, made in the rejoinder to the reply to the counterclaim for revocation, were too late.

Conclusion

In these decisions, the UPC demonstrates a pragmatic balance. With regard to applicable law and case amendments, the Court has clearly showed its intention to prevent procedural rigidity from hindering the fair and efficient resolution of disputes. In relation to the applicable test for DoE, the case law shows the UPC’s commitment to creating a unified approach to analysing equivalence, based on the shared principle that modified means must perform essentially the same function to achieve essentially the same technical result (or effect).

In future cases that go beyond the harmonised threshold, the complementary conditions that have emerged in national case law will certainly be adopted to strike the right balance between the patentee’s rights and third parties' justified interest for legal certainty. These could include the French “novelty of function” criterion, the German “obviousness to the skilled person” criterion, or the Dutch and German Formstein or Gillette defence, for example. It remains to be seen whether the UPC will choose between these to develop a fully harmonised, multi-step test, or continue to refer to them flexibly, adapting its reasoning to the specific circumstances of each case.

By Agathe Caillé, Max von Leitner, Nathalie Rodriguez, Carolin Wollschlaeger, Bumjoon Jang, François Jullienne