Anthropic just picked a fight with its biggest potential customer.

The AI company behind Claude filed a lawsuit Monday in the U.S. District Court for the Northern District of California naming the Departments of Treasury, Commerce, State, Health and Human Services, Veterans Affairs, the General Services Administration, and several other federal agencies as defendants.

Anthropic says the U.S. government effectively blacklisted its AI systems from federal procurement and did it without following any of the legal procedures required to actually ban a vendor.

It says there was a lack of formal determination, interagency review, documented evidence, and no evaluation of less restrictive alternatives like conditional approval or security audits.

According to the complaint, officials justified the restrictions internally on national security and supply-chain grounds, then let the directive spread informally through centralized procurement channels until Anthropic was locked out of federal contracting across the board.

The timing makes this more than a procurement dispute.

The U.S. government is in the middle of the largest AI adoption push in federal history, using OpenAI's ChatGPT as its tool of choice. Agencies are deploying generative AI for cybersecurity, intelligence analysis, administrative automation, and internal decision-making. The contracts are large, multi-year, and increasingly central to how the government operates.

Getting locked out of that market isn't a minor commercial setback, but an existential competitive problem for any AI company that wants to be taken seriously at the institutional level.

Anthropic is asking the court to declare the restrictions unlawful and block agencies from enforcing them. If it wins, the ruling would reopen federal procurement and potentially set a precedent on how far agencies can go when restricting AI vendors on national security grounds without following their own rules.

The government hasn't publicly responded to the filing, but an Axios report on Tuesday noted the White House was preparing an executive order formally instructing the federal government to rip out Anthropic's AI from its operations, citing sources familiar with the matter.