1. EPO Clarifies Claim Interpretation Standards: The G 1/24 decision mandates that the description and drawings shall always be consulted when interpreting patent claims under the EPC, resolving prior inconsistencies in Board of Appeal rulings.
  2. Global Alignment with National Practices: G 1/24 brings the EPO’s approach closer to that of the Unified Patent Court and several IP5 jurisdictions, though notable differences remain—especially regarding claim breadth and file history estoppel.
  3. Strategic Drafting for International Robustness: To ensure enforceability across jurisdictions, patent applicants should prioritize linguistic precision and consistent terminology.

On June 18, the European Patent Office published its landmark G 1/24 decision of the Enlarged Board of Appeal, concerning the principles of claim interpretation under the European Patent Convention (EPC).

In this article, we look beyond the EPO to the other IP5 countries – the US, China, Japan and Korea – and the Unified Patent Court to identify similarities and differences in claim interpretation, and how this knowledge can be used to draft globally robust patents.

In G 1/24, the Enlarged Board of Appeal considered the question of whether the description and drawings should always be used to interpret the claims, or should only be referred to when the claims are unclear or ambiguous – a question which had produced conflicting Board of Appeal decisions.

It found that the description and drawings “shall always be consulted to interpret the claims when assessing patentability.”

The Unified Patent Court

In a move that will be welcomed by European practitioners, G 1/24 serves to align the EPO approach to claim construction with that already adopted by the Unified Patent Court.

Moreover, G 1/24 – though technically binding only on the EPO – may exert an influence on future decisions by the UPC, whose rulings have already been shaped to some extent by EBA case law.

For example, in Abbot v Sibionics (first instance, ORD_30431/2024), The Hague Local Division explicitly refers to Enlarged Board decisions including G 2/10 and G3/89. And, while other UPC decisions are less explicit in acknowledging the EBA’s influence, NJOY v Juul Labs (ORD_598482/2023) has a distinctive “EPO flavour”, using the language of G 2/10 without expressly referring to the decision (see point 8.3 of the decision).

Some early UPC decisions took a highly unorthodox approach to claim construction, however. In SES Imagotag SA v Hanshow Technology Co Ltd (UPC_CFI_292/2023), the UPC looked back at the file history to interpret the claims.

On appeal, though, this approach was rejected, and the Court of Appeal cited principles, previously laid out in 10x and Harvard v Nanostring (UPC_CoA_335/2023 App_576355/2023), which are closely aligned with those subsequently set out in G 1/24:

“The patent claim is not only the starting point, but the decisive basis for determining the protective scope of a European patent. The interpretation of a patent claim does not depend solely on the strict, literal meaning of the wording used.”

“Rather, 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. However, this does not mean that the patent claim merely serves as a guideline and that its subject-matter also extends to what, after examination of the description and drawings, appears to be the subject matter for which the patent proprietor seeks protection. The patent claim is to be interpreted from the point of view of a person skilled in the art.”

The United States

While G 1/24 brings the EPO in closer alignment with the US, there are still differences between these two jurisdictions. US courts employ a well-established framework governed by precedent, most notably:

  • Markman v Westview Instruments, Inc, 517 U.S. 370 (1996), establishing that claim construction is a matter of law for the court;
  • Phillips v AWH Corp, 415 F.3d 1303 (Fed. Cir. 2005) (en banc), setting out the modern interpretive approach.

In Phillips, the Federal Circuit emphasized that “intrinsic evidence” – the claims, specification and the prosecution history – should be accorded the most weight. Claims should be construed in light of their ordinary and customary meaning as understood by a person of ordinary skill in the art at the time of the invention.

The specification is considered next from the point of view of the person of ordinary skill in the art, where claim terms are not only considered in the context of the particular claim but also in the context of the entire patent.

Notably, prosecution history estoppel can limit claim scope if the patentee made narrowing amendments or disclaimers during prosecution. Specifically, the prosecution history demonstrates how the inventor understood the invention and may demonstrate clear disavowals of claim scope.

While US courts consider extrinsic evidence (eg, expert testimony), such materials are generally considered far less persuasive and convincing than intrinsic evidence.

The US approach emphasises both public notice and technical clarity, balancing robust protection with predictable legal boundaries.

Japan

While Japanese claim construction therefore seems to be broadly harmonised with the EPO approach, one significant difference between EPO and Japanese patent office practice lies in the permissible claim breadth.

At the EPO, claims can generally be broader than the examples, provided that they represent a “reasonable extrapolation” thereof, judged on a case-by-case basis. In Japan, however, claims generally need to be much more closely aligned with the exemplified embodiments. This approach may simplify claim construction, although it does represent a significant challenge for applicants.

An important Japanese precedent is the Supreme Court’s Lipase decision, which concerned with a patent in which the term “lipase” was used in the claims, but the description used the narrower term “Ra-lipase”.

The Tokyo High Court construed “lipase” to mean “Ra-lipase”. On appeal, however, the Supreme Court held that only certain situations allow construction of claim language by referring to the specification of the patent application. Specifically, (1) if the technical meaning of the claim language is ambiguous or unclear; and/or (2) if an error in the claim language is apparent based on a reading of the description. Applying these to the term “lipase”, the Supreme Court found that no such special conditions applied, and therefore “lipase” had to be construed broadly.

More recently, though, Japanese courts have interpreted claims in light of the specification and drawings, finding Lipase to be subject-matter specific. For example, in IP High Court, 2009 (Gyo-ke) No. 10139, the court stated: “When interpreting the meaning of terms in the claims, the detailed description of the invention and the drawings contained in the patent application documents should also be consulted to clarify their technical significance, and a technically meaningful interpretation should then be adopted.”

China

Chinese patent law is based on the EPO Rules and Articles, and Article 64.1 of the PRC Patent Law is worded almost identically to Article 69 of the EPC. Therefore, like G 1/24, some additional interpretation via the case law has been necessary in China, via judicial interpretations.

Like the UPC, China has a bifurcated system in which validity and infringement are assessed independently, although in practice proceedings often run in parallel.

Claim interpretation in patent infringement cases has been stipulated in Judicial Interpretations (I), issued by China’s Supreme Court in 2009. Article 2 of Judicial Interpretations (I) stipulates that the courts shall determine the scope of the claims based on their content, in conjunction with the understanding that a person skilled in the art would have after reading the specification and drawings. Article 3 of Judicial Interpretations (I) further states that the courts may interpret a claim based on the specification and drawings, related claims, and patent prosecution files.

Article 6 of Judicial Interpretations (I) is also noteworthy for introducing estoppel, wherein the courts shall not consider, during a patent infringement dispute, the subject matter that was abandoned by amending the claims or specification or by making observations during prosecution or invalidation proceedings.

In 2016, the Supreme People’s Court issued Judicial Interpretations (II), providing further guidance on claim construction amongst other issues. Ten of the 31 Articles in Interpretations (II) relate to claim construction. Of note, Article 4 concerns errors in claims and discrepancies between the claims and the description. In such cases, the courts should use a sensible interpretation based on the understanding of a person of ordinary skill in the art.

In 2020, claim construction in infringement matters was harmonized with administrative cases (i.e., appeals of re-examination decisions and invalidation decisions issued by the CNIPA), see Article 2 of the Provisions of the Supreme People’s Court on Several Issues Concerning the Application of Law in the Trial of Administrative Cases Involving Patent Grant and Confirmation (I). Article 3 further establishes that: “[W]hen interpreting the terms of claims in administrative cases involving patent confirmation, the people’s court may refer to relevant statements of the patentee that have been adopted in effective judgments of civil patent infringement cases”, which is considered as a basis for applying reverse doctrine of estoppel practice in China.

Korea

A divergence in Korean case law on claim interpretation forced the country’s Supreme Court to intervene in 2014.

The apex court held that, in addition to the ordinary meaning of a term, the claims must generally be construed in light of the detailed description and drawings of the specification by defining the technical meaning of the claimed element in view of the purpose and effect of the claimed invention (Canon v Alphachem, Supreme Court Case No. 2012Hu917, July 2014).

G 1/24 therefore aligns Europe’s approach with Korean practice.

Best Practices for Global Patents

As such, G 1/24 brings the EPO’s approach to claim construction more closely into line with several key national patent courts.

It is, however, an important distinction that the EPO operates in three languages – English, French and German. This means that EPO examiners, Opposition Divisions and Boards of Appeal are frequently working outside of their native tongue and that subtleties of language can be missed. Consequently, clarity and precision of language is paramount, particularly when considering critical features in claims.

  • Explicit Definitions: Define key technical terms clearly in the specification. If multiple meanings are possible, select and anchor one.
  • Consistent Terminology: Avoid using synonyms for critical elements. What appears stylistic in English can create legal ambiguity in translation.
  • Avoid Vagueness: Qualitative terms should be linked to measurable criteria to avoid rejection or narrow interpretation.
  • Translation Sensitivity: For PCT applications, ensure technical nuance survives translation. If full human translation is not feasible, consider a hybrid approach (machine plus legal review), especially in high-risk markets like China and Japan.
  • Caution During Prosecution: Be mindful of the estoppel doctrines in the US and China. While there is no corresponding doctrine at the EPO, the file wrapper can be taken into consideration in certain situations, especially if the patentee appears to be inconsistent (see eg, T 0325/23, Point 6 of the Reasons). Avoid unnecessary narrowing statements or arguments unless required, as they may later bind the applicant in litigation.

Harmonization?

The decision in G 1/24 represents a meaningful step toward interpretive coherence within Europe, particularly between the EPO and the UPC. However, the global landscape remains fractured. While convergence exists on principles such as the role of the skilled person, critical divergences persist, particularly regarding file history estoppel and the extend of reliance on the description.

Practitioners should not assume harmonisation, but rather proactively manage divergence. Drafting strategy, linguistic precision, and prosecution conduct must all reflect jurisdiction-specific risks. By anticipating claim interpretation challenges and variations from the start, applicants can avoid costly errors and build robust, enforceable patent rights across markets.

Originally printed in IAM on October 23, 2025.