Getting to grips with validity at the UPC

Users of the patent system in Europe need to engage with how the Unified Patent Court (UPC) handles validity.

Validity at the UPC matters because of the court’s popularity. About 900 first instance cases and almost 300 appeals have been filed in just two years since the UPC began, and the numbers continue to rise. US claimants are the biggest users.

Here are five key messages, followed by a dive into recent case law for a deeper explanation of how validity is handled at the UPC.
 

Five key messages

1. It appears that the UPC will look at using the description to interpret the claims, so as patentee or challenger, make sure you take this into account.

2. Current EPO practice requires amendment of the description in line with amended claims, both in prosecution and opposition. But consider whether description amendments will impact claim interpretation. This is always advisable, including if UPC litigation is envisaged.

3. As a challenger attacking a claim, consider whether the impact of the description on claim interpretation could give you a novelty, inventive step or added matter attack.

4. The UPC uses the same strict added matter test as the EPO. In UPC validity proceedings, be prepared for added matter attacks akin to those of an EPO opposition.

5. The approach of the UPC to inventive step has not yet been nailed down, but is shaping up to be similar to the EPO approach. Preparations for inventive step attacks at the UPC will look similar to those in EPO oppositions. Run through multiple potential starting points for attacks.

For more detail, please read on.

Claim interpretation

The UPC approach to claim interpretation is based on the Court of Appeal decision in NanoString v 10x Genomics (UPC_CoA_335/2023). The patent in suit (EP4108782) claimed a method for detecting a plurality of analytes in a cell or tissue sample and several points required interpretation. The ruling required that the description and drawings must always be “used as explanatory aids” for claim interpretation – not only to resolve claim ambiguities, but always.
 
This approach has been followed in Sanofi v Amgen (UPC_CFI_1/2023), Regeneron v Amgen (UPC_CFI_14/2024) and, most recently, Agfa v Gucci (UPC_CFI_278/2023).
 
The EPO has a similar approach, with the Enlarged Board of Appeal stating in G1/24 that the description should always be “consulted” when interpreting claims – the EPO and UPC therefore being harmonised in both requiring reference to the description when interpreting the claims.
 

Added matter

The strict EPO “gold standard” on added matter is also used at the UPC. Amendments can only be made “within the limits of what a skilled person would derive directly and unambiguously, using common general knowledge, and seen objectively and relative to the date of filing, from the whole of these documents as filed”. Although subject matter can be implicitly disclosed, it must be “a clear and unambiguous consequence of what is explicitly mentioned”.
 
This was decided by the UPC Court of Appeal in Abbott v Sibio (UPC_CoA_382/2024). The patent in suit (EP3831283) claimed an on-body glucose sensor. A key question was whether omitting an elastomeric seal from the sensor added matter. The claims were based entirely on passages from the description. At first instance it was found that the description passages definitely required an elastomeric seal and leaving it out added matter. However, the Court of Appeal overturned this, using reasoning that resembles the reasoning used by the EPO, under a sub-test of the “gold standard”, for discerning whether omitting a feature from a claim is an unallowable “intermediate generalisation”:
 

78. … [I]n view of … the various ways of sealing mentioned in the original application, without any specific connection to any specific configuration, the skilled person does not discern a functional or structural relationship between the use of an elastomeric seal and the other features of these embodiments. Failing an inextricable link with the features of these embodiments, not including the use of elastomeric sealing in claim 1 cannot be considered as an intermediate generalization.

 
The bottom line is the UPC will use a similar or even identical approach to that used in prosecution and opposition at the EPO.
 

Inventive step

The UPC approach to inventive step is mixed, although clarity is expected in late 2025, with at least one case likely to require the Court of Appeal to address the issue.
 
The difficulty lies in that, in 2024, the Court of Appeal in NanoString v 10x Genomics decided on obviousness without applying a structured test for inventive step.
 
Lower courts have since applied a number of different tests. Some have used a “German” test. Others have used the EPO “problem-solution” test.
 
The “German” test involves identifying a “realistic starting point” document and then considering whether the skilled person would implement the claimed matter as a “next step”. Examples of first instance decisions applying this test include Sanofi v Amgen (UPC_CFI_1/2023), NanoString v Harvard (UPC_CFI_252/2023) and Syngenta v Sumi Agro (UPC_CFI_201/2024).
 
The EPO “problem-solution” test involves identifying a “closest prior art” document, identifying the distinguishing feature of the claim over the closest prior art, formulating an “objective technical problem” solved by the feature, and considering whether - faced with the objective technical problem - the claimed invention would be obvious to the skilled person. A key example of adoption of this test at the UPC is Edwards v Meril (UPC_CFI_501/2023), in which the court, while recognising that in most cases the German and EPO tests lead to the same outcome, nonetheless called for harmonisation with the EPO.
 
In the end, the UPC Court of Appeal seems likely to lay down a test that looks like that of the EPO, but probably wherein attacks can start from any realistic starting point document, which need not be the closest.
 

Looking ahead

In future, we can expect to see more certainty from the UPC Court of Appeal on inventive step, but already we have a clear picture of how the UPC treats other issues. The approach taken to validity at the UPC is shaping up to be very similar to that in EPO oppositions. This is good news for users of the system, who will welcome the clarity and certainty it affords.

If you have any questions relating to this topic, please get in touch with Nick Bassil, Anne-Marie Conn, Christine Pearson or your usual Kilburn & Strode advisor.
 
This article was written on 15 August 2025 and reflects case law at the time of writing.