Following·Day 2·first covered 22 Sep 2026·15 sources·updated 23 Sep 2026

AI labs antitrust suit over development pace

The gist

Subscribers Sue Four AI Labs Over Alleged Development Slowdown Pact

The suit tests whether public statements of mutual support among competing AI executives can constitute an antitrust violation under the Sherman Act. It frames a concrete governance dispute over whether AI safety coordination should be set by private agreement or by government, with potential consequences for how frontier labs structure any future joint safety commitments.

The full picture

A proposed class action, Buist et al. v. Anthropic PBC et al. (No. 3:26-cv-10693), was filed September 18, 2026, in the U.S. District Court for the Northern District of California, accusing Anthropic, OpenAI, SpaceXAI, and Google of violating Section 1 of the Sherman Act by allegedly agreeing to slow the pace of AI model development. The four named plaintiffs each pay for a subscription to one of the defendants' AI assistants: ChatGPT, Claude, Grok, or Gemini. The complaint is pled as an unlawful-per-se restraint and, in the alternative, under quick-look and rule-of-reason analysis, with plaintiffs seeking treble damages under the Clayton Act and an injunction. The alleged coordination is traced to September 12, when Anthropic CEO Dario Amodei published an essay calling to 'pace the frontier,' and rival CEOs Sam Altman, Elon Musk, and Demis Hassabis each publicly responded in agreement the same day. SpaceXAI LLC is identified as the entity through which Elon Musk controls the Grok chatbot business. The filing states plaintiffs are not challenging unilateral safety testing, outside evaluations, environmental safeguards, or government regulation.

How it developed

23 September 2026

A September 22 analysis called the suit, which accuses Anthropic, OpenAI, SpaceXAI, and Google of agreeing to slow AI development, legally thin, noting it cites no private communications and that three of the four plaintiffs are lawyers.

The analysis flagged a contradiction: lead attorney Nick Rowley warns of existential risk from uncontrolled AI while the plaintiffs simultaneously advocate for unconstrained AI development. A separate analysis warned the suit may push labs to abandon joint safety statements in favor of unilateral policies.

First citedRohan Paul Twitter The Neuron Zvi's AI Roundups forkast.news+3

22 September 2026

Reports emerged that OpenAI and Anthropic were close to a formal cross-testing agreement for their commercial models

Four paying subscribers to ChatGPT, Claude, Grok, and Gemini filed a federal antitrust class action on September 18, 2026, in the Northern District of California against Anthropic PBC, OpenAI Opco LLC, SpaceXAI LLC, and Google LLC, alleging the companies illegally agreed to slow AI model development. The complaint centers on September 12, when Anthropic CEO Dario Amodei published an essay urging industrywide AI deceleration and OpenAI CEO Sam Altman, SpaceXAI CEO Elon Musk, and Google DeepMind co-founder Demis Hassabis each publicly agreed the same day. Plaintiffs frame capability improvements as the product subscribers pay for, seek treble damages and an injunction, and explicitly exclude unilateral safety testing and government regulation from their claims. None of the four defendants had responded publicly at the time of filing.

First citedRohan Paul Twitter casrai.org en.cryptonomist.ch ailearningguides.com+5

21 September 2026

Eric Schmidt told The Economist that an AI pause is not realistic given US competitive incentives, framing development as a US-China race

20 September 2026

Further reporting explained the lawsuit's structure, identifying SpaceXAI LLC as the Grok entity and noting the per-se and rule-of-reason pleading alternatives

19 September 2026

Multiple outlets reported on the filed complaint; lead attorney Nick Rowley's governance framing published.

Sources

Rohan Paul Twitter

The Neuron