The file wrapper estoppel doctrine is once again rejected by the UPC

The Düsseldorf Local Division of the UPC recently issued a preliminary injunction in 10x Genomics Inc. vs Curio Bioscience Inc. (UPC_CFI_463/2023).

Interestingly, it is the second time that the patent prosecution history is not considered legally binding for interpreting the claims by a German Local Division for construing the claims, which reinforces the existing divergence at the UPC concerning the doctrine of file wrapper estoppel (also known as “prosecution history estoppel”), since at least one opposite opinion in that regard has been issued by another German Local Division.

Summary of the case

10X Genomics brought a claim against Curio Bioscience for infringement of European patent EP 2 697 391 B1 in the Federal Republic of Germany, the French Republic and the Kingdom of Sweden, due to marketing activities concerning two versions of the product “Curio Seeker Spatial Mapping KIT” taking place in those territories.

The protected invention relates to the localised or spatial detection of nucleic acids in a tissue sample. The patent at issue has two independent claims: one is directed at a method of localised detection of nucleic acids in a tissue sample comprising cells and the other recites an array for use in that localised detection.

In order to determine whether the patent right was infringed with a sufficient degree of certainty, the Local Division indicated that some features in the claims required interpretation. A topic of particular discussion was the interpretation of what constituted a suitable “tissue sample” within the meaning of the patent at issue. The defendant had a differing opinion in that regard and referred to statements made by the applicant during examination proceedings at the European Patent Office. However, the Local Division was in clear disagreement with that approach taken by the defendant.

In particular, the Local Division was of the view that statements made by the applicant during examination proceedings do not constitute admissible material for interpretation. They also noted that, consequently, those statements were generally not to be taken into account in the context of patent interpretation. It was only considered that, if the applicant has commented on the meaning of a feature or term during examination proceedings, that may at best be indicative of how a person skilled in the art would understand the relevant feature.

The Local Division further elaborated on that Art. 24(1)(c) UPCA and Art. 69 EPC provide the basis for determining which documents shall be used for interpreting claims and determining the scope of protection. Thus, they concluded that since the grant file is not mentioned in Art. 69 EPC, it does not strictly constitute admissible material for interpretation by law.


It is worth noting that the approach taken in 10x Genomics Inc. vs Curio Bioscience Inc mirrors that previously adopted by the same Düsseldorf Local Division in their order in Ortovox Sportartikel GmbH vs Mammut Sports Group AG and Mammut Sports Group GmbH (UPC_CFI_452/2023) dated April 9, 2024.

However, both orders from the Düsseldorf Local Division are polar opposites to the opinion issued by the UPC Munich Local Division in SES-imagotag SA vs Hanshow Technology Co. Ltd. et al. (UPC_CFI_292/2023). In that earlier order of September 2023, which concerned an application for interim measures, the claims of the patent application as filed were considered to be usable as an aid to interpretation of the patent at issue, in connection with amendments made during examination proceedings. However, no legal basis was then provided in support of file wrapper estoppel.


Only time will tell how the UPC will ultimately deal with the doctrine of file wrapper estoppel, though so far the UPC does not appear to have been significantly contributing to its harmonisation.

The fact that the UPC is composed of judges from all over Europe who are used to apply their corresponding national law cannot be disregarded and neither can the fact that Europe is divided on the application of this doctrine. By way of illustration, the doctrine of file wrapper estoppel is strictly applied in the Netherlands, whereas other countries such as France, Italy or Germany do not favor it.

In Spain, it is generally considered that the prosecution history may be submitted to the court and may be relevant to claim interpretation (cf. Danstar vs ACTIMAX BIO, Supreme Court decision of July 3, 2019, ECLI:ES:TS:2019:2244; Laboratorios Normon vs BIAL-PORTELA & CA., S.A., Barcelona Commercial Court No. 5 decision of April 6, 2021, ECLI:ES:JMB:2021:1155). However, this doctrine is only occasionally applied in practice. In parallel, it may be accepted that a patentee’s position cannot be inconsistent with its past position regarding the breadth of protection on the basis of the principle of good faith (venire contra factum proprium non valet), as long as that former position involves an unequivocal act with legal significance which is manifestly incompatible with the current position (cf. Oatly vs Nutrition & Sante Iberia et al., Barcelona Provincial Court No. 15,  ECLI:ES:APB:2016:508). However, this is not consistently applied by Spanish courts either.

In any case, now that the UPC is getting closer to its first birthday and the veils on what the future holds are slowly being lifted, one can only wonder whether it will eventually be such a patentee-friendly forum as initially thought.