Britannica, Merriam-Webster Accuse OpenAI of Copying Their Works

Encyclopaedia Britannica Inc. and Merriam-Webster Inc. accused OpenAI Inc. of “massive copyright infringement,” including copying the dictionary’s own definition of “plagiarize.”

OpenAI’s ChatGPT copies Britannica then uses the content to train its model and produce verbatim or near-verbatim answers, a Friday complaint in the US District Court for the Southern District of New York said. The suit also accuses the AI giant of trademark infringement when ChatGPT hallucinates false information and attributes it to Britannica or Merriam-Webster.

The suit mirrors a September complaint filed by Britannica and Merriam-Webster—owned by the Britannica—against AI-powered search engine Perplexity AI Inc. Both suits claim the AI companies infringe software in three different ways: mass-scale copying of protected content to train large language models to provide infringing outputs; retrieving, copying and using content upon a user prompt, and in generating infringing outputs.

The substantively overlapping complaints—both filed by Susman Godfrey LLP, which also represents news organizations and authors in other AI copyright suits—stressed that the AI platforms provide substitute products that compete with the content creators. Britannica said OpenAI markets ChatGPT as a way to get “useful answers on the web” without “digging through links to find quality sources and the right information.”

“But ChatGPT is only able to provide what it claims is a ‘better answer’ that doesn’t require ‘digging through the links’ by copying and misappropriating plaintiffs’ and other authors’ copyrighted content,” the complaint said.

OpenAI said in a statement that its models “empower innovation, and are trained on publicly available data and grounded in fair use.”

The complaint provided a side-by-side comparison of a Britannica article on education and ChatGPT’s output to a prompt asking for that article. The results matched nearly verbatim, but also included hallucinations, according to the complaint. It also said ChatGPT reproduced Merriam-Webster’s definition of “plagiarize” when asked for the dictionary’s definition.

Britannica said it reached out to OpenAI about licensing opportunities in November 2024, but OpenAI “never seriously pursued licensing” despite striking deals with “other similar publishers.” The complaint pushed back on the notion that ChatGPT makes fair use of its content, as the repackaged content has no new expression, meaning or message of its own.

The case is Encyclopedia Britannica Inc. et al v. OpenAI Inc., S.D.N.Y., No. 1:26-cv-02097, Complaint 3/13/26.