City Council Speaker Julie Menin issued a subpoena Monday to compel Elon Musk’s AI company to testify at next week’s sweeping Council hearing on artificial intelligence, after OpenAI, Google and Anthropic agreed to appear only after being warned they could face their own orders to appear at City Hall.

The Council said OpenAI, Google, Anthropic and Meta will now testify publicly under oath at the Oct. 5 Committee of the Whole hearing, which will bring all 51 Council members together to examine AI safety risks and a slate of proposed regulations.

Meta agreed to participate without the threat of a subpoena, according to the Council. But Google and Anthropic initially declined to appear by a Friday deadline, while OpenAI had also not confirmed its attendance.

Menin had been publicly warning for more than a week that the Council could compel the companies to appear. “We have subpoena power,” she told WNYC, adding: “We will if we need to.”

That threat became more concrete Friday, when Menin authorized the Council to issue subpoenas to the four companies that had not yet agreed to participate beginning at 9 a.m. Monday, and Council lawyers warned them subpoenas were coming. OpenAI and Google agreed Sunday, while Anthropic confirmed late Sunday night, according to the Council.

Musk’s company, SpaceXAI, did not respond to the Council’s requests, prompting Menin to issue the subpoena on Monday.

“Leading experts and AI executives themselves are warning about the potentially grave risks of rapidly advancing AI, and governments have a responsibility to act,” Menin said in a statement.

“These companies have a significant presence in New York City and collectively employ tens of thousands of New Yorkers,” she added. “Given the high stakes, these firms owe it to their workers and, above all, to the public to come before the Council, answer our questions, and provide input on our proposed legislation under oath.”

Menin initially invited the companies’ top executives — including OpenAI CEO Sam Altman, Anthropic CEO Dario Amodei, Google CEO Sundar Pichai, Musk and Meta CEO Mark Zuckerberg — to participate. But a Council spokesperson said Monday that other company representatives, rather than the CEOs, will testify on behalf of the firms that have agreed to appear.

amNewYork has reached out to each of the companies for comment and, for those that have agreed to appear, to confirm who will testify on their behalf.

The subpoena marks an escalation in Menin’s push to force some of the world’s largest AI companies into a public discussion over how New York City should regulate rapidly developing technology.

The Oct. 5 hearing will also examine a package of bills unveiled by Menin last week that could give AI whistleblowers a portion of fines or penalties recovered from companies that violate applicable laws, allow some people harmed by AI systems to sue companies and require third-party validation and human “kill switches” for AI systems marketed, offered for sale or deployed in the city.

The hearing comes amid mounting warnings from AI executives, researchers and whistleblowers about safety risks, including reports of AI agents circumventing controls during testing, as state lawmakers also weigh additional safeguards for large developers.

Under City Council rules, the speaker can issue subpoenas requiring witnesses to appear and testify under oath as part of a Council investigation.

If Musk’s company does not comply, the Council said it could ask the New York State Supreme Court to enforce the subpoena.