Extrajudicial admissions: can everything you say be used against you?

Patent owners and their representatives may make extrajudicial admissions during a patent's prosecution. For example, in Medinol v Janssen Pharmaceutica (C/03/01211) and Saint-Gobin v Knauf (2011/RG/01503), the plaintiffs attempted to broaden the scope of their claims. However, their arguments were found to contradict statements or specific claim limitations that they had made during their patents' prosecution. Therefore, the courts decided that the defendants had not infringed the patents concerned based on limited interpretations of the claims' scope.

Extrajudicial admissions are not limited to admissions made during a patent's prosecution. For example, in UVP v Telenet (A/11/05443), the court used the content of a corresponding patent application to support the interpretation of the claims of the patent concerned. Similarly, in Pfizer v Genentech (A/16/04171), the court nullified the patent concerned based on statements that the patent owner had made during foreign court proceedings, which apparently recognised that the prior art disclosed a composition which fell within the claims' scope.

Third parties can also make extrajudicial admissions. For example, in Bayer v Effik (A/12/04419), the defendant claimed that a component of its generic drug was prepared via a different process from the one claimed in the patent concerned. However, statements relating to this process that such a component's supplier had made during foreign court proceedings contradicted this claim. Therefore, the court decided that Effik had infringed Bayer's patent. In Willems Biscuiterie v Lotus (A/09/02830), the patent concerned was nullified based on a novelty-destroying prior art document, the publication date of which was disputed. A statement by the author of the document which had confirmed its publication date in an earlier court proceeding was found to be an extrajudicial admission.

Although parties may not have the option to remain silent, anything they do say can and may be used against them in court proceedings. Therefore, parties should take care when making public statements regarding patents or patent applications.