Sean Hutchinson

September 2025

We reported in our article of June 2025 that the decision of the EPO’s Enlarged Board of Appeal in G 1/24 seemed likely to “force a monumental change in practice at the EPO, whose examiners are very unlikely to now be able to raise objections against the claims of a European patent application based on an interpretation inconsistent with the description and drawings”. However, at least one commentary has recently reported that, rather than adopt this expected change in practice, the EPO has chosen to interpret G 1/24 as endorsing its current practice of requiring the claims of a European patent application to be clear in isolation (if necessary, to be amended so as to be clear in isolation), without reference to the description and drawings being needed.

The EPO’s apparent decision to interpret G 1/24 in this manner appears to be based upon paragraph 20 of the Reasons in that decision, which recites:

“The above considerations highlight the importance of the examining division carrying out a high quality examination of whether a claim fulfils the clarity requirements of Article 84 EPC. The correct response to any unclarity in a claim is amendment…”.

If the commentary is to be believed, then it would appear the EPO considers “a high quality examination of whether a claim fulfils the clarity requirements of Article 84 EPC” to involve checking that the claims are clear in isolation, and “unclarity in a claim” to arise from a reading of the claims on their own, with such unclarity only being rectifiable by making an amendment. However, this has started much debate as to what the Enlarged Board really intended by its Reasons and Order in G 1/24, and in particular whether the claims must be clear in isolation or in the context of the patent application as a whole, i.e. when considered together with the description and drawings.

In this regard, it is of note that the Enlarged Board stated in G 1/24 (at paragraph 16 of the Reasons) that:

“The Enlarged Board finds it a most unattractive proposition that the EPO deliberately adopt a contrary practice to that of the tribunals that are downstream of its patents.”

Those downstream tribunals are the national courts of the European Patent Convention (“EPC”) contracting states and the Unified Patent Court (“UPC”), all of which are responsible for administering European patents in their respective jurisdictions post-grant. Their practices are therefore important to consider when deciding how G 1/24 is to be correctly applied.

To use an example, the UK courts apply a practice of “purposive construction” when interpreting patent claims, the rationale being that claims should be interpreted according to what the skilled person would have understood the proprietor to have meant by the words it chose to use in the claims. This means that definitions provided in the description for terms used in the claims are generally to be read into the claims, despite not being explicitly recited in the claims themselves, and that interpretations of terms and features in the claims which are contrary to the description and drawings are generally to be avoided. These principles of claim interpretation are derivable from a large body of UK court case law, most notably including the decisions in:

• Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183 (HL),
• Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 (HL),
• Actavis UK Ltd v Eli Lilly & Co [2017] UKSC 48, and
• Icescape Ltd v Ice-World International BV [2018] EWCA Civ 2219.

Notably, the UK approach is similar to that applied by the UPC.

Specifically, in NanoString Technologies Inc v 10x Genomics, Inc (UPC_CoA_335/2023), the UPC’s Court of Appeal held that the “decisive basis” for determining the scope of protection conferred by a European patent is the claims and that “the interpretation of a patent claim does not depend solely on the strict, literal meaning of the wording used” but instead that “the description and the drawings must always be used as explanatory aids for the interpretation of the patent claim”. The UPC’s Court of Appeal emphasised that “these principles for the interpretation of a patent claim apply equally to the assessment of the infringement and the validity of a European patent”.

Similarly, in AGFA NV v Guccio Gucci SpA (UPC_CFI_278/2023), the UPC’s Hamburg Local Division held that the claims are “the authoritative basis for determining the scope of protection” but that, nonetheless, “a patent may be used as its “own lexicon”” such that definitions of certain terms used in the claims which are provided in the description must be applied when interpreting the claims.

The UK courts and the UPC thus appear to agree on two fundamental principles, namely that:

• the subject matter protected by a European patent is the subject matter which is claimed, not the subject matter which is described and/or illustrated in the drawings, and
• the claim wording is to be interpreted to have the meaning the skilled person would have understood the proprietor intended it to have based upon a reading of the description and drawings.

To put this another way, the UK courts and the UPC both recognise that one should read the description and drawings to understand the disclosed subject matter, and then treat the claims as ringfencing the part of that subject matter for which patent protection is sought. Importantly, neither the UK courts nor the UPC treat the claims as a standalone element to be read and understood in isolation, but rather as a part of a patent application / patent which is to be read and understood using the context provided by the description and drawings.

Turning back to G 1/24, it is noteworthy that the Enlarged Board of Appeal specifically identified these two fundamental principles and endorsed them at paragraph 12 of the Reasons for its decision. Here, the Enlarged Board stated that “the claims are the starting point and the basis for assessing the patentability of an invention under Articles 52 to 57 EPC” and “the description and any drawings are always referred to when interpreting the claims, and not just in the case of unclarity or ambiguity”, which is entirely in alignment with the above. In fact, at paragraph 19 of the Reasons, the Enlarged Board of Appeal even cited the above-mentioned Nanostring decision and confirmed the consistency between its decision and the UPC approach.

Setting the case law aside for a moment, one might even argue that these two principles are enshrined in statute, given that Article 69(1) EPC provides that “the extent of the protection conferred by a European patent or a European patent application shall be determined by the claims” (the first principle mentioned above) and that “nevertheless, the description and drawings shall be used to interpret the claims” (the second principle mentioned above).

It therefore seems clear that at least the UK courts, the UPC, and the Enlarged Board of Appeal agree on the correct approach to claim interpretation: the claims define the subject matter for which protection is sought (i.e., the invention), and the meaning of the words used in the claims is interpreted using the description and drawings.

When read in this light, one might argue that paragraph 20 of the Reasons in G 1/24 should be understood to mean that an EPO examiner should carefully use the description and drawings to interpret the claims and that, if a claim as interpreted is then considered unclear, the examiner should require the applicant to make an amendment to resolve the clarity objection.

This is notably, however, not the interpretation the EPO is believed to have chosen in its official guidance to its examiners. Instead, the EPO appears minded to maintain its current practice of requiring the claims to be written such that their meaning is clear from a reading of the claims in isolation. Interestingly, several recent decisions of the EPO’s Technical Boards of Appeal appear to interpret G 1/24 the same way.

For example, T 1561/23 held that “G 1/24 does not define what it means to use the description and drawings in an individual case” and that “G 1/24 does not even explicitly require that the definition of a term from the description must necessarily be used for the interpretation of a claim”. T 1999/23 then held that “a restrictive definition of the term in the description may not be used to limit the subject-matter of the claim, which is otherwise clearly broader for the skilled person”, that there is “no objective reason why a patent proprietor should be allowed to deviate from the established technical terminology in the formulation of the subject-matter from the use of which third parties are to be excluded without any discernible justification and to refer to this only in the description”, and that each term in the claims is therefore “to be understood in the sense of its customary technical meaning”.

In T 2027/23, the proprietor argued that G 1/24 required the Board to interpret the claims as being limited to a specific example disclosed in the description, despite the rest of the description clearly disclosing broader subject matter. Unsurprisingly, the Board held that such an approach to claim interpretation is incorrect, and stressed that “in cases of discrepancy between the claim language and the description, it falls upon the patentee to remedy this incongruence by amending the claim”, rather than it being “the task of the Boards of Appeal to reach such alignment by way of interpretative somersaults”. This decision is perhaps more in alignment with the approach of the national courts and the UPC than T 1561/23 and T 1999/23, given that it reinforces the principle that the claims define the subject matter for which protection is sought, not the description and drawings, even though the description and drawings are then to be used to interpret the wording of the claims.

Conclusions

The approach of the national courts and the UPC to claim interpretation is clearly set out in the case law. The wording of the claims determines the subject matter for which protection is sought, but that wording is to be interpreted in line with the description and drawings because the claims are not an isolated document, and thus cannot be read and understood out of the context provided by the patent / patent application as a whole.

The EPO’s purported guidance to its examiners, as well as the approaches taken in Board of Appeal decisions T 1561/23 and T 1999/23, however, appear to indicate the EPO is opting for a different approach to claim interpretation. Specifically, the EPO appears to favour an approach whereby the claims are treated as a standalone element of a patent application, with each term in the claims being interpreted according to the ordinary meaning of that term in the art, even if such an interpretation is contrary to the description and drawings.

Those following these developments in the case law will note that there is yet to be a Board of Appeal decision which addresses the specific question of whether a definition of a term used in the claims which is provided in the description should be assigned to that term when interpreting the claims, particularly in cases where the definition in the description is contrary to the ordinary meaning of the term in the art. As things stand, it appears the courts would hold that such a definition should be applied, whereas the EPO seems inclined to conclude it should not – although further case law from the EPO’s Boards of Appeal is needed to confirm this.

It is therefore very interesting to see that, despite the Enlarged Board finding that it would be “a most unattractive proposition that the EPO deliberately adopt a contrary practice to that of the tribunals that are downstream of its patents”, the EPO’s official guidance to its examiners seems to be that G 1/24 endorses its decision to do exactly that.

These developments suggest that, when drafting claims and corresponding description passages that provide definitions for terms in the claims, it may be best practice at the EPO to include a defined term in an independent claim, on the basis the term is defined in the description, but to also include a dependent claim explicitly reciting the definition. Cautious applicants would be wise to adopt such an approach for now, at least until further decisions of the EPO’s Boards of Appeal either confirm the EPO’s current approach or side in favour of the change in practice expected as a result of G 1/24.