The American Civil Liberties Union (ACLU) and the Center for Democracy & Technology (CDT) filed an amicus brief in Anthropic’s lawsuit in the D.C. Circuit Court of Appeals challenging the company’s designation as a “supply-chain risk” by the Department of Defense, which purports to prohibit anyone from using Anthropic’s tools in connection with Defense Department work. Anthropic’s lawsuit argues the designation was in retaliation for its First Amendment-protected advocacy related to artificial intelligence (AI) safety, including the urgent need for AI guardrails that prohibit the U.S. military from using these tools for fully autonomous weapons and mass domestic surveillance. The brief explains why Anthropic’s advocacy for AI guardrails is vitally important and describes the dangers posed by AI tools when applied to immense datasets containing sensitive information, including how these tools can invade privacy, chill speech, and facilitate discriminatory profiling. The groups also explain how existing U.S. privacy laws are inadequate to protect people in the United States, especially in light of loopholes the government has long exploited to justify sweeping surveillance, and emphasize why Anthropic’s advocacy for strict limitations on the government’s use of AI is critical to protecting the public’s privacy interests. The ACLU and CDT have been vocal supporters of the bipartisan Fourth Amendment Is Not For Sale Act, a commonsense reform bill that would ban the government from buying data.