Encyclopedia Britannica and Merriam-Webster sue OpenAI, claiming ChatGPT cannibalises nearly 100,000 of their articles

Filed in New York on 13 March 2026, the complaint accuses OpenAI of using the reference publishers’ content as AI training data without permission, then generating responses that reproduce it verbatim, six months after the same companies sued Perplexity on nearly identical grounds.

Encyclopedia Britannica and Merriam-Webster have filed a copyright and trademark lawsuit against OpenAI in the US District Court for the Southern District of New York, alleging that ChatGPT has been trained on and continues to reproduce their copyrighted content without authorisation, to the material detriment of both publishers.

The complaint, filed on 13 March 2026 (case no. 1:2026cv02097), accuses OpenAI of using nearly 100,000 of Britannica’s online articles as training inputs for its AI language models. The full extent of the copying, the complaint acknowledges, is only known to OpenAI itself.

Britannica, which owns Merriam-Webster as a subsidiary, argues that the law does not ...