IP High Court Clarifies Limits of “Motivation to Combine” in Patent Opposition Appeal

II. Background

The patent was registered on September 21, 2023, and the patent publication was issued on September 29, 2023. A patent opposition was filed on March 28, 2024, within the statutory six-month period from publication of the patent gazette. During the opposition proceedings, the patentee submitted amendments, which the JPO accepted. The JPO nevertheless revoked claims 1 to 7, 9 and 10, while maintaining claim 8.

The claims concerned, among other things, a hard coat laminated film comprising a hard coat, an anchor coat and a resin film layer, as well as a glass film for exterior use.

The JPO’s inventive-step analysis relied principally on a combination of two prior art references. Reference 2, the primary reference, disclosed a glass film for exterior use whose anchor coat layer used an ultraviolet absorber having a maximum absorption wavelength of 360 nm to 400 nm, with benzophenone-based absorbers identified as preferred. Reference 1 disclosed a benzotriazole-based ultraviolet-absorbing material in a laminated film for photocatalyst coating. The JPO considered that the benzotriazole-based UV-absorbing material disclosed in Reference 1 could be adopted for the anchor coat layer of Reference 2 and, on that basis, found the amended claims to lack inventive step.

III. IP High Court’s Analysis

The IP High Court focused on the wavelength requirement in Reference 2. According to the court, Reference 2 sought to provide a glass film for exterior use having excellent ultraviolet absorption characteristics, heat absorption characteristics, scratch resistance, transparency, weather resistance and coating adhesion. It addressed that objective by specifying different maximum absorption wavelength ranges for ultraviolet absorbers in different layers. In particular, the anchor coat layer required an ultraviolet absorber having a maximum absorption wavelength of 360 nm to 400 nm.

The decisive point was that Reference 1 did not disclose the maximum absorption wavelength of the benzotriazole-based compound relied upon by the JPO. Because that information could not be read from Reference 1, a skilled person would not know whether the compound satisfied the 360 nm to 400 nm requirement imposed by Reference 2 for the anchor coat layer.

The court therefore held that there was no sufficient motivation to adopt the compound of Reference 1 as the ultraviolet absorber for the anchor coat layer of Reference 2. It also found no technical common general knowledge that would bridge that gap. On that basis, the court annulled the JPO’s revocation of claims 1 to 7, 9 and 10.

IV. Practical Implications

This judgment offers three practical lessons.

First, a “motivation to combine” must rest on a concrete technical rationale. It is not enough that two references belong to a similar technical field. Where the primary reference depends on a specific technical parameter, the secondary reference must provide a sufficient technical basis for satisfying it.

Second, the decision underscores the value of parameter-based claim drafting and argumentation. Here, the wavelength requirement played a central role in defeating the JPO’s combination theory. In materials and composition cases, carefully framed technical parameters may therefore be important in opposition and appeal proceedings as well as examination.

Third, the case illustrates that Japanese courts are prepared to scrutinize JPO reasoning in opposition proceedings closely and, where appropriate, protect valid patent rights by overturning revocation decisions that lack an adequate technical foundation.

V. Conclusion

The January 15, 2026 IP High Court judgment is a significant decision on inventive step in patent opposition appeals. By rejecting a combination of references that lacked a sufficient technical basis, the court confirmed that the JPO’s finding of lack of inventive step could not stand where the alleged combination was unsupported by disclosure of a parameter treated as material in the primary reference.

For patent owners and practitioners, the decision highlights the importance of precise technical claim features and of challenging unsupported assumptions in JPO reasoning in opposition proceedings. It also serves as a useful example of the role of Japanese courts in ensuring that patent rights are not revoked without an adequately reasoned technical foundation.