EPO v UPC: How the EPO’s and UPC’s approaches to validity give us food for thought when drafting and prosecuting patent applications destined for Europe (Part 1)

The Unified Patents Court (UPC) opened its doors on 1 June 2023 and is already having a significant impact on EPO practice. Less than a year after opening, the UPC Court of Appeal (CoA) rendered its decision in 10x Genomics vs. NanoString (UPC_CoA_335/2023), ruling on how claims should be interpreted under the European Patent Convention (EPC). The CoA’s position was at odds with the EPO’s “classical” approach. This inconsistency played an influential role in prompting the EPO to reconsider how claims should be interpreted. In June 2025, the EPO’s Enlarged Board of Appeal (EBoA) (G1/24) brought the EPO’s approach to claim interpretation closer into line with UPC’s, finding “it a most unattractive proposition that the EPO deliberately adopt a contrary practice to that of the tribunals that are downstream of its patents”.  

The EBoA in G1/24 made the EPO’s harmonisation intentions very clear. However, harmonisation is not a new concept. When G5/83 issued some 46 years ago, the EBoA held that it was incumbent on the EPO to take the decisions of courts and industrial property offices in the EPC Contracting States into consideration. But G5/83 did little to promote harmonisation. However, since G1/24, there has been a palpable change, and we are beginning to see the EPO make significant strides to align its approach on validity with the UPC’s. Conversely, while the UPC is developing its case law independently of the EPO, many aspects of UPC case law have been shaped by the EPO’s approach to validity.  

In this four-part series, we explore the similarities and differences between the EPO’s and UPC’s approach to claim interpretation, added matter, novelty, sufficiency and inventive step. As well as influencing litigation strategies, these similarities and differences give us food for thought when drafting, prosecuting and managing patent portfolios destined for Europe. 

In the first part to this series, we take a detailed look at claim interpretation.  

Claim Interpretation 

Before the Technical Board of Appeal (TBA) in T439/22 asked the Enlarged Board of Appeal for clarification on claim interpretation, many European patent attorneys would have argued that, if a term in a claim was clear, there was no need to refer to the description to interpret the claim, the latter only being required to resolve ambiguities. While there were earlier TBA decisions requiring the description to be consulted in the absence of ambiguities, these decisions were in a minority and, in the main, still upheld the principle that the claims had primacy2, thereby limiting the influence of the description on claim scope.  

In G1/24, the Enlarged Board turned this established practice on its head, ruling that: 

“The claims are the starting point and the basis for assessing the patentability of an invention… The description and drawings shall always be consulted to interpret the claims…, and not only if the person skilled in the art finds a claim to be unclear or ambiguous when read in isolation.” 

This echoed the UPC CoA’s approach set out in 10x Genomics vs. NanoString, which held: 

“The patent claim is not only the starting point, but the decisive basis for determining the protective scope of a European patent… [T]he 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 rules for claim interpretation at the EPO and UPC are now simple; the claims are the basis and starting point for claim interpretation, but the description and drawings must be consulted when interpreting the claim.  

Simplicity, however, does not necessarily lead to predictability. In the wake of G1/24, many TBA decisions3 continued to uphold the principle that the claims had primacy over the description. Thus, while the TBAs in these decisions “consulted” the description, they did not necessarily consider restrictive features of specific embodiments to be limiting on the wording of the claims. These decisions were broadly in line with the UPC’s decision in Kinexon v Ballinno (UPC_CFI_230/2024 ), in which the Paris Central Division (CD) held that a claim should not be limited to an understanding derived from the more specific or narrower features disclosed in a dependant claim or in the description.  

However, in T1999/23 and T1561/23, the TBA went further to hold that even a restrictive definition4 of a term in the description could not be used to limit the subject-matter of a claim that the skilled person otherwise interpret more broadly. For instance, in T1999/23, the TBA applied G1/24 but held that a definition that was inconsistent with the clear technical meaning of the term used in the claim could not have precedence over the clear technical meaning; this was contrary to legal certainty.  

The TBA’s approach in T1999/23 was in sharp contrast with the approach taken by the Board in T439/22. In the latter, the TBA interpreted G1/24 as requiring a consideration of the claims and the consultation of the description as a unitary process. In other words, rather than looking first at the claims and then revisiting their meaning in the light of the description, the TBA held that the correct approach was a holistic one, in which a skilled person reading the claim in the context of the description and figures would try to take a definition found in the description at face value. Provided that the definition was technically reasonable and complied with the overall teaching of the patent a skilled person would read the definition into claim, accounting for any broadening or limiting aspects of the definition.  

The holistic approach as set out in T439/22 has now been endorsed in G1/25. Although G1/25 is primarily directed to description amendments, the decision relies on the principles of claim interpretation in G1/24 to determine the circumstances in which the description needs to be adapted to the claims to meet the requirements of the EPC. In relying on G1/24, G1/25 also endorsed T439/22’s approach on how G1/24 should be applied. Since this endorsement underpins the EBoA’s rationale in G1/25, T439/22 may now be binding on future EPO decisions. If this turns out to be the case, this will have implications when assessing e.g., freedom to operate as greater care must be taken to ensure that a seemingly narrow term used in the claims has not been defined in a broader (or worse, nebulous) way in the description. It may also be difficult to assess whether a definition taken at face value is technically reasonable and compliant with the overall teaching of the patent as required by T439/22. This may make it more difficult for parties to assess their freedom to operate risks. 

With the approach of T439/22, it is also unclear whether the EPO will consider the ordinary meaning of a claim term to emerge directly and unambiguously from the disclosure of the patent if the description defines the term in a different (broader or narrower) way. Although the claims are deemed as the starting point for claim interpretation, the TBA in T439/225 interpreted the EBoA’s reasoning in G1/24 as excluding the possibility of performing any “interpretative act” without considering the description at the same time (unitary process). Accordingly, if a claim term is defined in the description in a way that differs from its otherwise clear meaning, it may perhaps no longer be possible to rely on the clear meaning of the term to restrict the claim if the sole basis for this clear meaning arises from the claim in isolation. By way of example, consider a scenario where the agreed meaning of the term “emulsion” is dispersion of liquid particles suspended in a liquid. If this term is defined in the description broadly as a dispersion of particles (i.e., not necessarily liquid particles) suspended in a liquid, then, following T439/22, this definition may well override the agreed meaning of “emulsion”6, such that dispersions such as colloids that would not usually be considered as emulsions would be deemed to fall within the definition of the claim. Without a clear and unambiguous disclosure that the dispersed particles in the emulsion are liquid, it may not be possible to limit the term “emulsion” to its ordinary meaning without adding subject matter. In other words, if the claim is to be interpreted in the light of the description as a unitary process, it may be questionable whether the ordinary meaning of the term would be considered to emerge directly and unambiguously from the claim alone. This is because T439/22 seems to interpret G1/24 as excluding any “interpretative acts” on the claims alone. 

A further consequence of the approach endorsed in G1/25 may be an increased risk of Article 123(2)/123(3) traps where the patentee is unable to amend a patent after grant to address an added matter objection without impermissibly broadening the scope of the claim. Consider again the scenario relating to the term “emulsion”. During prosecution, the definition is deleted on the assumption that the claim term can then rely on its ordinary meaning rather the broader definition being deleted from the description. If, however, the ordinary meaning is not regarded as directly and unambiguously derivable from the application as filed because claim interpretation must be performed as a unitary exercise in the light of the original disclosure, the granted claim may subsequently be vulnerable to an Article 123(2) EPC objection. At the same time, the patentee may be unable to restore the deleted definition to the description because doing so could broaden the meaning of “emulsion” and thus the scope of protection, contrary to Article 123(3) EPC. 

In view of the above, extra care should be taken when including definitions when drafting patent applications. This applies to definitions of terms used in the claims but may also be relevant to definitions of terms used in the description, as terms used in the description may be later incorporated into the claims during prosecution. As should be the norm when drafting patent applications destined for Europe, it is advisable to include fallback positions e.g., in the form of narrower or nested definitions so that there is basis for restricting definitions of terms if required. Similarly, during prosecution, it can no longer be assumed that a claim will be interpreted on its face to have its ordinary meaning. Accordingly, while it is no longer compulsory to adapt the description to the claims under all circumstances post-G1/25, it may be advisable to take care during prosecution to ensure that, if definitions are included in the description, these reflect how the terms in the claims are intended to be defined. Even if the ordinary meaning of the claim language achieves this purpose, definitions in the description that are too broad may override the meaning of the claim and “catch” prior art, drawing the claim’s validity into question. Conversely, narrower definitions used in the description may restrict the otherwise broader claim language, increasing the risk of third parties escaping infringement.  

Many commentators have welcomed the G1/24 and G1/25 as bringing the EPO’s approach to interpretation into line with the UPC’s. On a high level, this is broadly the case. However, by endorsing the specific approach of T439/22 to the application of G1/24, G1/25 appears to have endorsed an approach that is more prescriptive than that set out by the UPC CoA in 10x Genomics vs. NanoString. For example, 10x Genomics vs. NanoString is silent on the circumstances in which definitions in the description should be taken at face value to override the otherwise clear meaning of terms used in the claims. Rather, 10x Genomics vs. NanoString places emphasis on the requirements of Article 69 EPC and its Protocol on the Interpretation (“the Protocol”), confirming that the claim should be interpreted to provide adequate protection for the patent proprietor with sufficient legal certainty for third parties. It is unclear how the UPC will strike a balance between, on the one hand, definitions that diverge from the otherwise clear meaning of claims and, on the other, the need for adequate protection and legal certainty. Specifically, how far can a definition diverge from an otherwise clear meaning of a term in a claim without compromising legal certainty for third parties? The answer will no doubt be fact dependent. One thing is for sure; this will be a difficult problem to untangle in the context of providing freedom to operate advice.  

It also remains to be seen how G1/25’s endorsement of T439/22 squares with how the EPO interprets the claims for added matter. At the EPO, claims are generally given their broadest technically sensible interpretation. In this context, there have been TBA decisions7 that consider all technically sensible interpretations of a claim feature when assessing compliance with Article 123(2) EPC. These decisions warn against interpreting claim features in the light of the description in such a way as to limit the claim to an interpretation that complies with Article 123(2) EPC, as this would prevent added matter from being assessed objectively, jeopardising legal certainty. The approach in these decisions is now called into question by G1/25’s endorsement of T439/22. If, as we suspect will be confirmed in G1/268, the approach of T439/22 is held to apply to added matter, we may see a relaxation in the EPO’s approach to added matter, as the claims will not be interpreted to cover subject matter that is not supported by an interpretation of the claims in the light of the description.   

US readers may also be interested to know that the UPC CoA has also ruled on how “means plus function” claims should be interpreted. In Abbott v Sibio [UPC_CoA_382/2024], the CoA held that, as a general principle of claim interpretation, means-plus-function features must be understood as any feature suitable for carrying out the function. This is consistent with the approach taken by the EPO. 

Finally, regarding the file wrapper, several decisions9 of the TBA have confirmed that there is no file wrapper estoppel under the EPC. Amending a claim in response to a novelty or inventive step objection, therefore, is not an admission that the claim lacks novelty or inventive step prior to amendment. This does not mean that submissions made in earlier proceedings have no consequence on future proceedings. In T325/23, an interpretation put forward by the patentee during examination was relied upon by the TBA to confirm that the interpretation was “technically sensible”. A similar approach was taken by the UPC CoA in Alexion v Samsung (UPC_CoA_402/2024). Here the court took the assertions made by the patentee during grant proceedings and the Board’s endorsement of them as being indication of the views of a skilled person at the filing date of the patent. Accordingly, at both the UPC and EPO, patentees may find it difficult to row back on positions on interpretation taken in earlier proceedings. Patentees, therefore, should take care when making assertions on claim interpretation as these may have an impact on later enforcement or validity proceedings.  

Table 1: Summary of EPO’s and UPC’s approaches to claim interpretation 

Key Takeaways 

• At both the EPO and UPC, the claims are the starting point and basis for claim interpretation, but the description must always be consulted to interpret the claims. 

• At the EPO at least, definitions will be taken at “face value” provided that the definition is technically reasonable and complies with the overall teaching of the patent.  

• Care should be taken when drafting, particularly if definitions are included in the text. This applies to terms that are not in the claims as these terms may be included in the claims during future prosecution or post-grant proceedings. Nested definitions should be considered to provide fallback positions for restricting the definition of terms.  

• Care should be taken when amending definitions to ensure that these amendments find basis in the original text. Depending on the facts, it may not always be possible to amend a term to its ordinary meaning if the term is only defined differently in the original application. 

• Means plus function features are interpreted broadly. 

• There is no file wrapper estoppel, but assertions made with respect to how a skilled person would interpret a claim may affect how claims are interpreted in future proceedings at the EPO and UPC.  

Part 2 coming soon.

This article was prepared by Hsu Min Chung, Thomas Compton & Robert Scanes.