Background

RPN, a French company specializing in drainage systems, alleged that First Plast’s “ghost” drainage cover infringed EP 938, specifically claims 1 and 5 to 9, which protects a gutter channel and cover assembly partially concealed under floor coverings to ensure drainage and alignment. EP 938 requires “at least two longitudinally aligned spacer elements” while First Plast’s ghost grid featured a single continuous rib.

RPN brought claims based on literal infringement and infringement by equivalence against First Plast regarding France, Italy, and Spain. First Plast denied all claims and did not counterclaim for revocation.

Key issues and the Local Division Paris’s analysis

File wrapper estoppel is considered

To support its claim for literal infringement, RPN argued that the transverse portions of First Plast’s ghost rib constituted the claimed spacer elements while the longitudinal portions had no technical function. Although such an argument might have been acceptable, the Local Division Paris recalled that statements made during prosecution may influence claim construction.

Referring first to the principle set out in the UPC Court of Appeal’s (CoA) decision in Alexion Pharmaceuticals, Inc. v. Samsung Bioepis NL B.V., the Local Division Paris ruled that statements made during the grant procedure generally have only indicative value as they “can be seen as an indication of the view of the person skilled in the art at the filing date.” However, the Local Division Paris held that the situation is different when the patentee goes beyond mere statements and actively relies on them to amend the patent application to overcome a novelty objection. In the present case, RPN considered the two parallel walls disclosed in the prior art to be essential for spacing the covering elements, therefore constituting a single spacer element. Thus, RPN could not subsequently argue in the framework of the infringement proceedings that the allegedly infringing continuous rib should be treated as two distinct spacer elements. Since First Plast’s ghost rib consisted of a single continuous element, it did not comprise the “at least two spacer elements” required by the patent claims. The Local Division Paris therefore rejected literal infringement.

This approach to file wrapper estoppel slightly departs from the position adopted in Ortovox Sportartikel GmbH v. Mammut Sports by the Local Division Düsseldorf on December 11, 2023, which held that the grant file should not be taken into account when interpreting a patent. According to that decision, Article 24(1)(c) of the UPC Agreement (UPCA), read in conjunction with Article 69 of the European Patent Convention, exhaustively lists the relevant materials for claim construction (namely, the description and the drawings) while statements made during examination would, at most, have an indicative value as to how a person skilled in the art may understand the feature in question without limiting the scope of protection.

In the present case, however, the Local Division Paris expressly endorsed a file wrapper estoppel principle. Its reasoning echoes the position adopted in SES-imagotag SA v. Hanshow Technology by the Local Division Munich on October 11, 2024, which held that earlier versions of the claims may be used as an interpretation aid where amendments were made during the grant procedure.

Such reasoning reflects a broader concern for consistency throughout the life of a patent. Under such an approach, the patentee’s statements and actions during examination – particularly where claims were narrowed to overcome invalidity objections – may legitimately be relied upon against the patentee in infringement proceedings, preventing patentees from narrowing and then broadening of scope of protection depending on whether validity or infringement is at stake.

The development of the doctrine of equivalence

RPN also claimed infringement under the doctrine of equivalence. The UPCA, however, does not provide a specific test for infringement by equivalence.

In the absence of an agreement between the parties on which national test should apply, the Local Division Paris, referring to the decisions in NJ Diffusion SARL v. Gisela Mayer GmbH from the Local Division Paris on August 1, 2025, and in DISH Technologies L.L.C v. AYLO from the Local Division Mannheim on June 6, 2025 (See also decisions from the Local Division The Hague in Plant-e Knowledge B.V. v. Arkyne Technologies S.L. on November 22, 2024, and the Local Division Brussels in OrthoApnea S.L. on January 17, 2025), applied a comparable approach to equivalence stemming from various national doctrines within the UPC Member States. In Plant-e Knowledge v. Arkyne Technologies, the Local Division The Hague defined the test for infringement by equivalence via a series of guiding questions regarding:

• Technical equivalence: Does the variation solve (essentially) the same problem that the patented invention solves and perform (essentially) the same function in this context?
• Fair protection for the patentee: Is extending the protection of the claim to the equivalent proportionate a fair protection for the patentee, and is it obvious to the skilled person from the patent publication how to apply the equivalent element at the time of infringement?
• 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?
• Novelty and inventiveness of the allegedly infringing product: Is the allegedly infringing product still novel and inventive over the prior art?

In the present case, the Local Division Paris focused on the functional criterion: Are the modified (or substituted) means essentially performing the same function to achieve essentially the same effect? This is not surprising from the Local Division Paris as this focus is close to the test set by the French Supreme Court, consistently holding that infringement by equivalence is excluded when different means do not perform the same new function to achieve the same result. The Local Division Paris answered this question in the negative and did not examine any further criteria as the ones set for instance by the Local Division The Hague.

In the present case, the continuous rib of First Plast’s ghost grid was found not to reproduce the core functions of the claimed spacers, namely providing longitudinal alignment for the covering elements and defining evacuation openings. The Local Division Paris also noted that the claimed improvement in water drainage was neither described nor credibly derivable from the patent specification. It is worth noting that the Local Division Paris emphasized that the burden of proof lies with the plaintiff, and that the patentee cannot simply assert that the interpretation of the invention is obvious to a person skilled in the art: “The proprietor must demonstrate that the functions not described in the patent could have been deduced by a person skilled in the art and that his allegation is more likely than not (UPC_CoA_523/2024, decision of 3 March 2025).” In the present case, RPN did not demonstrate that the modified means essentially fulfilled the same function, as the alleged function did not clearly follow from claim 1 and was not easily deducible by a person skilled in the art.

As a result, the allegedly infringing product did not achieve the same technical effect and the threshold for equivalence was not met. The Local Division Paris therefore rejected RPN’s claims for infringement under the doctrine of equivalence.

Conclusion

The Local Division Paris’s decision to apply a principle of file wrapper estoppel confirms some local divisions of the Court of the First Instance’s broader objective of legal certainty and consistency in claim construction, preventing a patentee from narrowing and then broadening a claim’s scope of protection depending on whether the patentee is at the examination or enforcement phase.

With respect to the doctrine of equivalence, the Local Division Paris appears to be moving toward a function-based approach, which is arguably only one of several cumulative criteria in the Court of First Instance’s overall analysis. On both issues, some further guidance and even a precise test from the CoA appear necessary to provide parties with legal certainty when assessing the overall prospects that a patent is valid and infringed.