Can Digital Simulations Be Used to Assess Patent Infringement?

Digital simulations can be used to analyse the technical features of a product. But can simulation results establish whether an actual product infringes a patent?

This question arose in a procedural order issued by the Munich Local Division of the Unified Patent Court (UPC) on 15 September 2026 in SWARCO v. Yunex (UPC_CFI_245/2025 and UPC_CFI_618/2025).

The dispute concerns European patent EP 2 643 717 and optical components used in traffic signal systems. SWARCO alleges that the products supplied by Yunex infringe the patent.

1. Simulating a Product Is Not the Same as Examining the Product

The judge-rapporteur clarified that the accused embodiments were the optical components actually installed in traffic signal systems in Mönchengladbach, Germany. Based on findings from earlier inspection proceedings, the court assumed that a sample purchased by the claimant had the same configuration.

The judge-rapporteur then addressed the use of digital simulations:

“Untersuchungen der optischen Eigenschaften von digitalen Simulationsobjekten [können] den Nichtverletzungsnachweis nicht erbringen, soweit nicht bewiesen ist, dass eine Übereinstimmung mit den streitgegenständlichen Optiken besteht.”

In essence, an analysis of digital simulation models cannot establish non-infringement unless the models are shown to match the optical components at issue.

The reasoning is straightforward. A simulation produces results for a particular model, not necessarily for the physical product it is intended to represent. Even if the simulation itself is technically sound, its results may not establish the characteristics of the accused product.

The crucial question is therefore whether the model accurately represents the relevant features of the actual product.

Importantly, the order does not reject digital simulations as evidence in principle. The judge-rapporteur's concern was that, without proof of correspondence between the simulation models and the accused optical components, the simulation results could not establish non-infringement.

2. No Second Opportunity to Examine the Actual Products

Following this clarification, the defendant requested permission to examine the accused optical components and submit further written arguments. The intervener supported the request, while the claimant opposed it.

The judge-rapporteur rejected the request, stating:

„Dass Yunex sich entschieden hat, dies nicht zu tun, sondern stattdessen digitale Simulationsobjekte untersucht hat, rechtfertigt kein weiteres Schriftsatzrecht.“

In other words, Yunex had had sufficient time to examine the accused optical components but chose to rely on digital simulations instead. That choice did not justify granting it an additional opportunity to file written submissions.

The judge-rapporteur also found that no taking of evidence on this issue was necessary at the oral hearing.

The procedural point is significant. A party choosing to rely on simulations must address the relationship between its models and the accused products within the applicable procedural timetable. If that relationship has not been established, the party may not be given another opportunity to examine the physical products and supplement its defence.

The order does not determine whether the patent has been infringed. It nevertheless highlights an important distinction: The technical validity of a simulation is not the same as its evidentiary value in patent infringement proceedings.Even a technically accurate simulation cannot reliably establish the characteristics of an accused product unless the model is shown to correspond to that product. In this case, without such proof of correspondence, the simulation results could not establish non-infringement.

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Subsequent developments in legislation, case law, administrative practice or official guidance may affect the accuracy or continued relevance of the content.