EPO Appeal case provides further guidance on claim interpretation
Case Law | 29.01.2024
Can the description be used for claim interpretation, and if so, when? This question has been a major topic of recent EPO case law. Lasse Weinmann, Leo Polz and Sebastian Giese of HOFFMANN EITLE’s Munich Office were involved in an EPO Appeal case which provides further guidance on claim interpretation (T 42/22).
The discussion of added subject-matter in that case was focused on the question of whether a chemical group of the claimed modified nucleotide, the “3'-azidomethyl” group, was to be interpreted based on its literal wording and chemical standard (IUPAC) nomenclature – in which case claim 1 would contain added subject-matter –, or whether the description could be used to reinterpret the contested feature as “3'-O-azidomethyl”.
In its decision, the Board 3.3.04 considered, as a first point, the skilled person’s understanding of the claimed term based on common general knowledge. It found that in the prior art in the field, it was common to use the standard (IUPAC) nomenclature to describe defined chemical groups, and concluded that the standard nomenclature was therefore applicable to the contested feature in the claim at issue.
The Board then turned to the question of whether the description had to be considered in order to reinterpret the claim. It confirmed earlier case law stating that if a claim is clear as such and can be interpreted in a technically sensible way, the description should not be used for claim interpretation. The Board reasoned that in the case at hand, the claim was clear, because there were no inconsistencies in the claim. In this regard, the Board also indicated that in situations where multiple readings of a claim are possible, it is not necessarily justified to use the description for interpretation. If the claim merely comprises several embodiments which can be identified, this does not constitute an ambiguity, and hence, the description should not be considered.
Finally, the Board also commented on the question of whether claim 1, which was a product claim, should be interpreted in the context of another independent claim, method claim 6. The Board disagreed with the Patentee’s view that an independent product claim is to be interpreted based on a method claim and considered that neither the case law nor Art. 84 EPC supports such an approach to claim interpretation. The Board, however, also added that in the case at hand, this legal question was not decisive, because claim 6 allowed a technically sensible claim interpretation which was compatible with the Board’s interpretation of the contested feature in claim 1. The Board noted that even if additional interpretations of a claim are possible, a technically sensible interpretation – which in this case resulted in a finding of added subject-matter – cannot be disregarded.
Accordingly, the patent was revoked due to added subject-matter.
Congratulations to Lasse Weinmann, Leo Polz and Sebastian Giese who dealt with this case. We think that this decision provides additional guidance on claim interpretation and may thus help to increase legal certainty for third parties.