Using the prosecution file in the UPC? An idea from the UK

In SES-Imagotag v Hanshow (20 December 2023), the Munich Local Division of the UPC appeared to open the way to using the prosecution file for claim construction. In that case, the original claim form of a European patent was used to resolve an ambiguity in the granted claim. 

On appeal, the Court of Appeal (13 May 2024) re-evaluated the facts and found that the allegedly infringing embodiment did not fall within the scope of the claims for other reasons. It did not have to consider the issue of the prosecution file and so the issue was left to one side. 

But the question remains whether this is possible.

SES-Imagotag contrasts with the decision by the Local Division Dusseldorf in Ortovox Sportartikel v Mammut (11 December 2023). Here, it was held that the granted file was not to be taken into account when interpreting the patent. Instead, it was said, Article 24(1)(c) UPCA in conjunction with Article 69 EPC conclusively determine which documents are to be used in the interpretation of the patent claims, namely the patent description and the patent drawings. Mere statements made during the grant procedure do not initially have any significance in limiting the scope of protection. 

In 10x Genomics v Curio Bioscience (30 April 2024), the Dusseldorf Division again held that statements made by the applicant in the granting procedure were not admissible material for interpretation. 

So far, the issue has not been satisfactorily resolved. But, must the use of the prosecution file be an all or nothing matter?

Recent cases in the UK suggest there are, very limited, circumstances in which the prosecution file may be used as an aid to interpretation, without opening the floodgates to use in every case.

In Actavis v Eli Lilly (12 July 2017), the UK Supreme Court (which also follows Article 69 EPC) is sceptical about reliance on the prosecution file. However, it sets out two situations in which it may be appropriate to use its contents:

• the point at issue is truly unclear if one confines oneself to the specification and claims of the patent, and the contents of the file unambiguously resolve the point, or
• it would be contrary to the public interest for the contents of the file to be ignored.

These two sets of circumstances are relatively narrow: the granted patent does not itself resolve the issue, and the file does; or there has been an express statement that the patent would not be asserted against the type of variant at issue.

Subsequently, there has only been one case in which the prosecution file was relied on. This was in Akebia v Fibrogen (20 April 2020). 

In Akebia, the facts fell into the public interest category: the patentee had stated to the EPO during prosecution that they would not seek to assert their patent against prior art compounds, and they subsequently did assert it against those compounds in the Patents Court.

What the UK authority shows, however, is that facts of the kind that were assessed at first instance in SES-Imagotag v Hanshow may fall into the first category from Actavis – resolution of ambiguity that cannot otherwise be resolved – allowing that decision to be reconciled with the general principle in the other UPC cases that the prosecution file is not to be relied upon.