Recently, the Board of Appeal of the European Patent Office (EPO) issued its first decision regarding the use of artificial intelligence to assist in claim interpretation, making it clear that ChatGPT cannot replace a skilled person in interpreting patent claims (Case No. T 1193/23).

Rieter was granted patent EP 3 118 356 on November 4, 2020, relating to a procedure for safely starting and/or stopping the rotor of a rotor spinning machine used for yarn production. Saurer filed an opposition against this patent at the EPO. After examination, the EPO Opposition Division upheld the patent on April 18, 2023. Dissatisfied with the decision, Saurer appealed to the EPO Board of Appeal. Rieter requested dismissal of the appeal or, alternatively, maintenance of the patent in amended form based on one of five auxiliary requests. Rieter argued that certain technical features in the contested patent claim were not disclosed in the prior art if the claim language was properly interpreted. Notably, Rieter relied on answers obtained from ChatGPT to explain the meaning of relevant terms in the disputed claim.

On May 14, 2025, the Board of Appeal issued its decision, overturning the Opposition Division’s ruling and revoking the patent, finding that claim 1 lacked novelty and that the auxiliary requests lacked novelty or inventive step. The Board noted that because Rieter did not submit the full ChatGPT responses or the details and context of the questions in writing, the content of the ChatGPT answers could not be taken into account.

The Board further explained that ChatGPT’s responses were irrelevant since claim interpretation depends on the understanding of the skilled person. The mere widespread use of AI chatbots such as large language models does not justify assuming that an answer—based on unknown training data and highly sensitive to the context and wording of questions—necessarily replaces or undermines the skilled person’s understanding at the relevant time.

Moreover, the Board confirmed that “suitable specialist literature” can be used to demonstrate how a skilled person understands specific terms in patent claims, but no such evidence was submitted by Rieter in this case.