Authors Alliance argues 'market dilution' is not a copyright harm in OpenAI litigation amicus brief

What happened

On 29 October 2026, Authors Alliance asked the court for leave to file an amicus brief in In re OpenAI, Inc. Copyright Infringement Litigation, the consolidated copyright cases against OpenAI and Microsoft pending before Judge Sidney Stein in the U.S. District Court for the Southern District of New York. The brief supports the defendants' motions for summary judgment on one issue only: whether "market dilution" is a kind of harm copyright law recognizes.

The argument

Market dilution is the idea that copying works to train an AI model harms the market for those works because the model can then generate new works that compete with them, even if those new works reproduce no protected expression and are not themselves infringing. Authors Alliance argues it is not a cognizable copyright harm: copyright gives authors control over the market for their protected expression, not a right to be free from competition by works that borrow only ideas, facts, genres and methods. The brief traces the theory to Judge Chhabria's 2025 decision in Kadrey v. Meta, notes Judge Alsup rejected a similar argument in Bartz v. Anthropic, and argues the class plaintiffs have asked Judge Stein to adopt it.

Why the group says it matters

Authors Alliance says treating dilution as harm would hurt many of the authors the theory claims to protect, because a rule broad enough to shield an incumbent author from noninfringing AI-generated competition would also shield incumbents from noninfringing human competition that fair use enabled. It takes no position on the other questions in the case, such as how OpenAI acquired its training data or whether particular model outputs infringe.