Düsseldorf Local Division, May 27, 2026 – UPC_CFI_807/2024 & UPC_CFI_334/2025
In a significant decision on the doctrine of equivalents, the Local Division Düsseldorf has expressly adopted the four-step test previously developed by the Local Division The Hague, providing further guidance on how patent infringement by equivalence will likely be assessed before the Unified Patent Court (UPC).
The case concerned EP 1 905 615 relating to a stroller wheel swivel locking device. While the Court upheld the validity of the patent and rejected the defendants’ revocation counterclaim, it dismissed the infringement action, finding that the accused stroller products did not infringe the patent either literally or by equivalent means.
I. The Emerging UPC Doctrine of Equivalents
Noting that the UPC Court of Appeal has not yet established a definitive test for infringement by equivalence, the Local Division Düsseldorf endorsed the four-step test developed by the Local Division The Hague in Plant-e v Arkyne and Washtower v BEGA (UPC_CFI_239/2023, Decision of November 22, 2024, para. 88 – Plant-e v Arkyne; UPC_CFI_479/2025, Order of September 11, 2025, p. 23 – Washtower v BEGA).
Under this test, a claimant must establish (see para. 239 of the decision):
- Technical equivalence – Does the variation solve (essentially) the same problem that the patented invention solves and performs (essentially) the same function in this context?
- Fair protection for the patentee – Is extending the protection of the claim to the equivalent proportionate to a fair protection for the patentee? 46 This needs to be assessed in view of the patentee’s contribution to the art and taking into account the question whether it is 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 alleged equivalent – Is the allegedly infringing product novel and inventive over the prior art?
The Court considered these criteria to form a coherent whole and as suitable for examining patent infringement by equivalent means.
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Technical Equivalence – A Structured Feature-by-Feature Analysis
The most notable aspect of the decision is the Court’s assessment of technical equivalence. The patentee argued that the accused products merely reversed the arrangement of several components while achieving the same overall objective, providing a secure connection between rotatable and non-rotatable parts of the stroller wheel assembly (para. 241 et seq. of the decision).
The Court rejected this approach. It held that it is not sufficient to focus solely on the objective task of the patent. Rather, what matters is the function of each exchanged features in achieving this task. This includes, according to the Court, the function of the arrangement and location of the respective components, as set out specifically in the claim. In the Court’s view, equivalence requires a structured, feature-by-feature functional analysis rather than a broad comparison of end results.
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The “fair protection” criteria
The Court also addressed the “fair protection” criteria of the test (para. 256 et seq. of the decision). It found that the question that needs to be answered is whether extending the protection of the claim to the equivalent is proportionate to a fair protection for the patentee. This needs to be assessed in view of the patentee’s contribution to the art and taking into account the question whether it is obvious to the skilled person from the patent publication how to apply the equivalent element (at the time of infringement). The Court answered this question in the negative. It found that given the specific requirements regarding the arrangement of components set out in the patent, several components of the claimed device would need to be rearranged to arrive at the challenged embodiment. In the Court’s view, such a fundamental redesign would not be obvious to the skilled person. After all, several parts would have to be rearranged simultaneously (para. 263 of the decision).
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Legal Certainty Remains Central
The Court further found that extending protection to the accused design would undermine legal certainty. The patent claims specified a particular arrangement of components, and the patent itself presented that arrangement as central to achieving the invention’s technical objective. A skilled person would therefore not understand the patent as extending to substantially different structural configurations.
II. Key Takeaways
This decision represents a very detailed analysis of infringement by equivalence to date and potentially strengthens the emergence of a harmonised UPC approach. Three practical lessons stand out:
- The Düsseldorf Local Division has now expressly aligned itself with The Hague’s four-step equivalence test.
- Claimants must provide a detailed feature-by-feature explanation of why a substituted element performs substantially the same function; reliance on the overall purpose of the invention will not be sufficient.
- Where the alleged equivalent requires a fundamental redesign of the claimed solution, a finding of equivalence is likely to be difficult.
Until the Court of Appeal provides definitive guidance, Wonderland v Cybex will likely serve as a leading UPC guidance on the infringement by equivalence and the evidential burden faced by patentees seeking protection beyond the literal wording of their claims.