Making the fictional skilled person real: the first oral examination of expert witnesses at the Unified Patent Court

Patent disputes often hinge on the "skilled person," a fictional representation of someone working in the relevant technical field. While most European courts typically rely on documentary evidence, some courts use expert witness testimony to bring this figure to life. The Unified Patent Court allows for both. Hoffmann Eitle Partners Mark Jones, David Sproston and European patent attorney William Liu were involved in a recent case before the Nordic-Baltic regional division that saw the first oral examination of expert witnesses, suggesting this division may be receptive to such testimony in complex technical disputes. 

At the heart of most patent disputes is a crucial individual: the skilled person, through whose eyes the patent specification, the prior art, and the original disclosure are to be read.  There are differences in the approach to determine the skilled person’s attributes in various jurisdictions. The Boards of Appeal of the European Patent Office (EPO) include technically-qualified members alongside legally-qualified members whereas in some national judicial proceedings, Court-appointed experts can play a greater role, and will typically be appointed in Italian patent proceedings, for example. Such a practice is far from universal however, as court technical experts are rarely appointed in French or Dutch patent proceedings. Germany, with its bifurcation of infringement and validity proceedings, presents a further variant in which the validity (nullity) Court is composed by three technically-qualified judges and two legally-qualified judges whereas the infringement Court will typically not have the benefit of a court-appointed expert or any technically-qualified judge. The UK system, on the other hand, heavily relies on expert witness testimony, with cross-examination playing a crucial role in shaping the Court’s understanding.

The Unified Patent Court (UPC) is Europe’s new Court system for  patent disputes. While the UPC’s Rules of Procedure provide for the appointment of both party and court-appointed experts, an early decision of the Munich local division showed that this division in particular, felt no need to have either an expert appointed by the Court, or party experts heard1. However, the Abbott v Dexcom dispute has reopened this question. The case in question was one of a series of cases addressing continuous glucose monitoring (CGM) technology forming part of a global litigation between the parties, involving disputes in the USA and Europe, including national, EPO a nd UPC proceedings. The patent at issue, EP 3 977 921 B1, related to methods and devices for inserting a glucose monitoring assembly into a person’s skin, which assembly was configured to provide glucose data to a remote device (such as a smartphone) by Bluetooth wireless communication technology. 

Interpretation of the patent claims and the novelty and obviousness of the claimed invention were disputed by the parties, and both parties had adduced expert statements from well-respected individuals involved in the development of medical devices in support of their cases. During the written procedure it was already clear that the party experts, who contributed a number of written statements, differed substantially on several key issues. In view of these differences , the parties asked the Court for the opportunity to present their experts in oral examination before the oral hearing. The court, composed of legally qualified judges from Sweden, Estonia, and Italy, along with a French technically qualified judge, granted this request. This order of the Court led to the first ever oral examination of witnesses in proceedings before the UPC, in December 2024. 

The hearing of witnesses was in order indicated by the Court, with strict time limits per expert of twenty minutes per round of questioning allocated. After each witness had been taken through the sequence of examination, cross-examination and questioning from the Court, each party was given the opportunity to recall one or more of the witnesses for further questions before the evidence session was closed. It is notable that the witness hearing seemed effective in bringing the skilled person, and the circumstances surrounding them at the relevant date, to life, with each expert having the opportunity to show the Court not only what their views were, but why they held them, and in particular the strength of conviction behind each key statement. The court permitted a transcript to be taken, to ensure clarity and to reduce disputes over witness statements.

This was the first instance of oral expert examination in UPC proceedings. Although the case settled before a decision was reached, it is plain from the willingness of the Court to hear the witnesses, the close attention paid by the Court to the examination and cross-examination, and the careful questioning by the Court, and in particular the technically-qualified judge, to the witnesses, that the Court saw value in  examining expert testimony in this way. Parties who feel that the attributes of the skilled person, and the common general knowledge, at the relevant date are unlikely to be represented by documentary evidence, for example in fast-moving technical fields, may find the Nordic-Baltic regional division an attractive venue for litigation before the UPC.

However, it is clear that, in particular with the front-loaded nature of the UPC proceedings, the typical one-to-two day trial schedule which is the norm in UPC proceedings, and the need to appropriately conserve the Court’s resources, parties should present compelling reasons as to why the hearing of expert witnesses would be appropriate. Moreover, it is clear from the experience before the Nordic-Baltic regional division that both judges and litigation teams with deep experience in examination of witnesses are available within the UPC system, and so a party adducing an expert witness should ensure that they are clear and convincing not only on paper, but moreover should they be required to take the witness stand.  

[1] UPC_CFI_15/2023