Carlsen Verlag, author Mark‑Uwe Kling and illustrator Astrid Henn filed suit on 19 August 2026 at the Munich I Regional Court against OpenAI Ireland Ltd., which operates ChatGPT in Europe. The plaintiffs say simple prompts produce new NEINhorn stories that reproduce core creative elements of the books, and that generated illustrations are almost indistinguishable from the originals. During tests, ChatGPT reportedly suggested new texts and illustrations related to the series even when users did not mention those characters, and it produced mock‑ups including a cover, fictional ISBN and the publisher's logo.
The suit demands that OpenAI stop unlicensed use of protected works, disclose possible infringements and compensate rights holders. Carlsen is backed in the case by the Bonnier publishing group and seeks a precedent that copyrighted works may be used to train AI only with rights‑holder consent. The filing follows earlier German litigation against OpenAI over a children’s series and broader industry protests against training AI on copyrighted material.