Claim interpretation at the EPO: key lessons from the application of G 1/24 by Technical Boards of Appeal

Background

In G 1/24, the Enlarged Board of Appeal, the highest level of judicial authority of the European Patent Office (EPO), decided on the circumstances in which the description and drawings should be used to interpret patent claims when assessing the patentability of an invention.

According to the Enlarged Board, the claims are the starting point and the basis for assessing the patentability of an invention under Articles 52 to 57 of the European Patent Convention (EPC). However, the description and drawings shall always be consulted to interpret the claims when assessing the patentability of an invention, and not only if the person skilled in the art finds a claim to be unclear or ambiguous when read in isolation.

So, what does consulting the description and drawings to interpret the claims entail? To answer this question, this article reviews some early Technical Board of Appeal decisions that applied G 1/24 to reveal emerging principles and considerations by the Boards.

Key lessons from the application of G 1/24 by the Technical Boards of Appeal

• The wording of the claims forms the basis for their interpretation: The Board in T 2027/23 provided a thorough commentary on G 1/24. The Board reasoned that “it cannot be inferred from [G 1/24] whether the description and the drawings should be ‘consulted’ for the purpose of, for example, deriving ‘explanatory aids’ to claim interpretation…, confirming the ordinary meaning of a claim feature, determining the function or the purpose of a claim feature, or simply defining the technically skilled reader of a claim”. The Board went on to reason that ‘G 1/24… does not require the Boards to give the description preference over the wording of the claim.’ To the contrary, the Board in T 2027/23 considered that the claims are the ‘decisive basis’ for their interpretation.

• Principles of claim interpretation developed by the case law remain relevant: The Enlarged Board in G 1/24 explained that while there is no clear legal basis in terms of an article of the EPC for claim interpretation when assessing patentability, the applicable principles of claim interpretation can be extracted from the existing body of case law. Several Board of Appeal decisions have referred to this part of the reasoning in G 1/24 and subsequently applied one of those established principles to the case at hand. Examples include T 1999/23 and T 2027/23.

• Narrow definitions in the description cannot be used to limit claims: The Board in T 1999/23 confirmed that this established principle remains valid after decision G 1/24. The claim at issue in T 1999/23 included the term ‘excitation surface’ without definition, while the description provided a definition of the term that was narrower than the conventional technical meaning. The Board interpreted the term ‘excitation surface’ for the purpose of assessing patentability as having its conventional meaning, reasoning that the Board saw no objective reason why a patent proprietor should be allowed to deviate from established technical terminology without any justification and to refer to this only in the description. The reasoning of the Board in T 1999/23 was followed in T 1465/23, T 0161/24 and T 1846/23. Other decisions following this principle include T 0400/23 and T 2027/23.

• Broad definitions in the description can result in claims being interpreted broadly: This was the decisive issue in T 0439/22 that resulted in the Board referring questions to the Enlarged Board of Appeal, leading to G 1/24. In T 0439/22, the claim at issue included the term ‘gathered sheet’. The description included a definition of ‘gathered sheet’ that provided a broader reading of the term than if the claim were construed in isolation. Whilst not a decision and only a preliminary opinion, the Board issued a communication including its preliminary opinion that the effect of G 1/24 is that the term ‘gathered sheet’ must be interpreted by consulting the description, and, since the broader reading imparted by the description is technically meaningful, the broader reading should be followed.

• Claim interpretation between national courts or the Unified Patent Court (UPC) and the Boards of Appeal should be harmonised: In T 2027/23, the Board elaborated on major takeaways from G 1/24, one of these being that ‘discrepancies in claim interpretation practice between national courts, the UPC and the Boards of Appeal are undesirable and should thus be avoided.’ Indeed, in T 2027/23, the Board referred to judicial precedents on claim interpretation from the UPC and the German Federal Court of Justice when it reasoned that ‘A claim should not be interpreted, based on features set out in embodiments of an invention, as having a meaning narrower than the wording of the claim as understood by the person skilled in the art.’

• Claims are interpreted as having their broadest technically sensible meaning: In T 1069/23, the proprietor argued that, in view of the description and a figure, the claim at issue should be interpreted in a way that excluded certain embodiments. The Board did not accept this argument and saw ‘no reason to deviate from the wording of the claim and cut down its scope by implying into it additional features which appear only in the description of a specific embodiment.’ The Board pointed out that the broader interpretation of the wording of the claim also made technical sense and was encompassed by the description as a whole. Therefore, the established principle of interpreting a nonspecific definition according to its broadest technically sensible meaning in the context of the claim remains.

• Only technically illogical interpretations of claims are ruled out: The patent in suit in T 1069/23 related to disposable wearable articles, defined in an auxiliary request as having, inter alia, leg elastic members. The prior art disclosed a disposable wearable article having elastic members, which the opponent asserted were leg elastic members as defined in claim 1. The proprietor argued that the particular elastics at issue did not correspond to leg elastic members as defined in claim 1. The Board did not accept this argument, noting that ‘according to the case law of the Boards of Appeal, only technically illogical interpretations of a claim should be excluded’ and that the interpretation made by the opponent would not be illogical.

Conclusion

While the claims of a European patent (application) form the basis for their interpretation when assessing the patentability of an invention, the description and drawings must be referred to. It therefore remains the case that the whole patent specification needs to be prepared carefully and skilfully. Discrepancies between the claims and the description can result in weaknesses that may be exploited by opponents during EPO opposition proceedings, which may potentially prove fatal to the validity of the patent.

Please contact us if you would like to discuss the potential relevance of G 1/24 to your business, or email gje@gje.com.