Key Takeaways:
- The Enlarged Board of Appeal (EBA) of the European Patent Office (EPO) issued its opinion in G1/24 on June 18, 2025 resolving divergent case law on how patent claims should be interpreted at the EPO.
- The EBA has now clarified that a patent's specification and drawings should "always be consulted to interpret the claims" during prosecution, including terms expressly defined in the specification. It held that this must always be done, and "not only if the person skilled in the art finds a claim to be unclear or ambiguous when read in isolation."
- This decision brings claim construction at the EPO further in step with the U.S. and U.K.
- However, it remains to be seen whether there is any meaningful difference between the EBA's clarification that the description should always be "consulted" to interpret the claims, rather than "used" to interpret them.
G1/24 and EPC Article 69(1)
The issue presented to the EBA in G1/24 was whether Article 69(1) of the European Patent Convention (EPC), including the requirement that the description and drawings be used when interpreting claims, applies not just in post-grant revocation and infringement proceedings, but also during prosecution, i.e., when assessing patentability of an invention under Articles 52 to 57 of the EPC.
Article 69(1) of the EPC states: "The extent of the protection conferred by a European patent or a European patent application shall be determined by the claims. Nevertheless, the description and drawings shall be used to interpret the claims."
Article 1 of the Protocol on the Interpretation of Article 69 EPC further explains that:
As explained by Lord Neuberger in the case of Actavis v Eli Lilly, "the Protocol bears all the hallmarks of the product of a compromise agreement" because "[t]here is an inevitable conflict between the desirability of giving an inventor an appropriate degree of protection in a particular case and the need for clarity of principle as to the extent of such protection generally."
The EPO's Technical Board of Appeal referred the issue presented in G1/24 to the EBA from pending appeal T 0439/22. The appeal arose from the opposition division finding that the claim term "gathered sheet" had a clear and agreed meaning widely adopted in the relevant industry. As such, the opposition division found the patent's specification was not required to interpret the claims, even though it expressly provided a broader definition of "gathered sheet." In doing so, the opposition division applied the principle of "primacy of the claims"—this restricts use of the patent's specification to exceptional cases where the claimed subject-matter needs to be clarified, which, it held, was not the case here.
This was a key finding. As the Technical Board of Appeal explained, if the term "gathered sheet" is given its usual meaning in the art then the subject-matter of claim 1 is novel, whereas if this term is read in a broader but still technically meaningful manner in view of the patent specification's definition then claim 1 lacks novelty. Because of divergent case law at the EPO, the Technical Board of Appeal referred the issue to the EBA. In particular, it asked whether Article 69(1) and Article 1 of the Protocol on the Interpretation of Article 69 EPC are to be applied to the interpretation of patent claims when assessing the patentability of an invention under Articles 52 to 57 EPC.
In its recent decision, the EBA clarified that "the description and drawings shall always be consulted to interpret the claims when assessing the patentability of an invention" during prosecution "and not only if the person skilled in the art finds a claim to be unclear or ambiguous when read in isolation." That includes terms expressly defined in the specification.
The U.S. and Lexicographers
While claims define the metes and bounds of a patentee's invention, the U.S. likewise construes claims in light of the specification. Claim terms are generally given their plain and ordinary meanings to one of skill in the art when read in the context of the specification and prosecution history. The U.S. recognizes two exceptions to this rule: (1) when a patentee sets out a definition and acts as his own lexicographer, provided the meaning does not contradict the term's language itself; or (2) when the patentee disavows the full scope of a claim term either in the specification or during prosecution. Said differently, after giving a claim its plain and ordinary meaning, the court determines whether the patentee has redefined the term in a more limited or broadened way.
In the seminal case, Phillips v AWH, the Federal Circuit made clear that the "specification may reveal a special definition given to a claim term by the patentee that differs from the meaning it would otherwise possess. In such cases, the inventor's lexicography governs." The lexicography standard is exacting. The patentee must clearly express an intent to redefine the term beyond its plain and ordinary meaning. For example, in Thorner v Sony a specification repeatedly used the term "attached" in reference to embodiments where a particular component is attached externally on a controller, but never where that component is located inside a controller. Nevertheless, "attached" was given its plain and ordinary meaning absent express lexicography.
During patent examination, pending claims are given their broadest reasonable interpretation consistent with the specification, although, if the claims cannot be amended—such as during litigation—then they are construed as a person having ordinary skill in the art would understand them. But even during patent examination, "words of the claim must be given their plain meaning, unless such meaning is inconsistent with the specification." MPEP § 2111.01. As such, the applicant may act as their own lexicographer before the USPTO by clearly setting forth a special definition of a claim term in the specification that differs from its plain and ordinary meaning.
Claim Construction Before the UK and UPC
The EBA's recent decision found that referring to the description only in cases of unclarity or ambiguity to be "contrary to the practice of the national courts of the EPC states [including the UK] and to the practice of the UPC."
Indeed, UK courts apply the overarching principle in Article 69 of the EPC to claim construction. When considering claim construction, UK courts ask what a skilled person would have understood the patentee to be using the words of the claim to mean. This is an exercise of purposive construction—ascertaining the inventor's purpose from the description and drawings. For example, as summarized by the Court of Appeal in Saab Seaeye v Atlas, "where a patentee has used a word or phrase which, acontextually, might have a particular meaning (narrow or wide) it does not necessarily have that meaning in context." The U.K's patent office has also explained that "[i]n approaching the construction of the claims the specification as a whole should be read to obtain the necessary background, and in some cases the meaning of the words used in the claims may be affected or defined by what is said in the body of the specification." Manual of Patent Practice § 125.17.1.
In a recent case involving RSV vaccines, Pfizer v GSK, all claims of the asserted patents required an RSV antigen that comprised a particular "polypeptide." The parties disputed whether the term "polypeptide" required a single chain of amino acids joined together through amide bonds, or whether it should be interpreted more broadly, to include dimers made up of more than one polypeptide joined together by non-amide bonds. The patents' common specification defined the term polypeptide using the former, narrower definition. The defendant, however, argued that the term should be given its ordinary meaning as used in the field. The High Court held that "it is plain that [the patent] contains its own dictionary, providing a precise and technically accurate definition of the term 'polypeptide' for all purposes (i.e. both infringement and validity). It is clear that the [p]atent uses that and other terms accurately.... The Patentee chose to include that definition. It could have defined the term more broadly, but that might have caused other issues and it chose not to do so." GSK also asserted its RSV-based patents against Pfizer in the U.S., although that case was dismissed before the scheduled claim construction hearing.
The EBA has likewise aligned itself with the approach adopted by the Unified Patent Court (UPC). Last year in a headnote in Nanostring, the UPC Court of Appeal found that "the description and the drawings must always be used as explanatory aids for the interpretation of the patent claim and not only to resolve any ambiguities in the patent claim."
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
