The federal government on Tuesday defended the Pentagon’s decision to blacklist Anthropic, arguing in a court filing that the move was lawful and driven by national security concerns.
On March 9, Anthropic filed two federal lawsuits – one in the U.S. District Court for the Northern District of California and another in a federal appeals court in Washington, D.C. – alleging the Trump administration violated its First Amendment rights and exceeded the legal scope of a supply chain risk statute. The company is seeking a federal injunction to block defense officials from enforcing a blacklist designation.
The case stems from an ongoing dispute between Anthropic and the Department of Defense, rebranded as the Department of War under the Trump administration. The conflict centers on Anthropic’s refusal to allow its artificial intelligence (AI) models to be used for mass domestic surveillance or in fully autonomous weapons. Pentagon officials have argued that the department wants to be able to use the AI without “having to call Anthropic for permission to shoot down enemy drone swarms that target Americans.”
In the court filing, the Trump administration said Anthropic is unlikely to succeed in its claim that the designation violated its First Amendment rights, asserting that the dispute stems from contract negotiations, not retaliation.
“It was only when Anthropic refused to release the ?restrictions on the use of its products – which refusal is conduct, not protected speech – that the President ?directed all federal agencies to terminate their business relationships with Anthropic,” the legal filing said, adding that “no one has purported to restrict Anthropic’s expressive activity.”
The government also argued that Anthropic’s efforts to limit how the Pentagon could use its AI technology led the government to reasonably conclude that the company posed a potential risk to national security systems.
Anthropic has until Friday to file a counterresponse.
The legal battle has drawn widespread attention – and support for Anthropic – from across the technology sector, legal community, and former military leadership.
However, much of the support focuses less on Anthropic’s stance and more on concerns about the federal government’s actions in the dispute.
Tech support
Anthropic gained early backing in its California case from employees of OpenAI and Google, who filed an amicus brief describing the supply-chain risk designation as “an improper and arbitrary use of power” with broad implications for the technology sector.
Microsoft also filed a separate brief supporting Anthropic’s request, citing its business relationship with the company and warning of potential disruptions to existing defense-related technology systems. Microsoft argued that a temporary restraining order would allow for a more orderly transition, avoid harming ongoing military operations, and provide time for a negotiated resolution.
The company added that it supports lawful and carefully controlled uses of AI, while cautioning against applications such as domestic mass surveillance or autonomous systems capable of initiating conflict.
Support from former military chiefs
A group of former service secretaries and retired senior military officers also filed an amicus brief in support of Anthropic’s request.
The group argued that actions taken by the federal government lack a firm legal foundation and could weaken the military and undermine longstanding public-private partnerships.
While acknowledging that the dispute arose from disagreements over safeguards for rapidly developing AI technologies, the group said its concern was more fundamental: the potential misuse of national security authorities by civilian leadership as retaliation against a private company.
Support from legal experts and advocates
A coalition of advocacy groups and legal experts, including the Foundation for Individual Rights and Expression, Electronic Frontier Foundation, Cato Institute, Chamber of Progress, and the First Amendment Lawyers Association, filed the most recent amicus brief.
The filing argued that the government’s actions constitute a violation of First Amendment protections, asserting that Anthropic is being pressured to alter its systems and policies to align with government demands. The brief contends that such pressure amounts to compelled speech and retaliation for the company’s expressed views.
The coalition further argued that the designation threatens Anthropic’s business operations and could set a precedent allowing the government to penalize companies for ideological differences.