Legal technology startup Legion has filed a lawsuit in Washington, D.C., challenging a US government directive that restricted foreign nationals from accessing Anthropic’s Fable 5 and Mythos 5 foundational models. The complaint, filed Tuesday, alleges that the sudden cutoff of access has caused immediate, irreparable, and existential harm to the company’s operations and competitive position. Earlier this month, Anthropic suspended access to its flagship models following a formal request from US authorities concerned about potential security vulnerabilities and model jailbreaks. To ensure compliance, the AI laboratory initially disabled access for all users before implementing nationality-based access controls and enhanced onboarding screening. The directive explicitly barred foreign individuals and entities from using the platforms, a policy that directly impacted Legion’s workforce. Founded in 2024 and headquartered in San Jose, Legion develops artificial intelligence-driven litigation drafting software that automates the creation of pleadings, discovery requests, and other legal documents. The company’s platform relies heavily on frontier language models, including Fable 5. According to the lawsuit, Legion is a commercial customer holding a contractual license to access the model. The government restriction abruptly severed access for Canadian nationals working remotely from Canada, effectively halting key aspects of the company’s development cycle. Legion argues that in the rapidly evolving AI sector, even brief interruptions can irreversibly damage a startup’s market standing against better-capitalized competitors. The litigation represents the first known legal challenge from an Anthropic customer regarding the administration’s recent push to tighten regulatory oversight of frontier artificial intelligence systems. While Anthropic has defended the pause as a necessary precaution against narrow security risks, customers and industry observers increasingly view the blanket restrictions as an overreach that disrupts commercial deployment and restricts global talent mobility. The Department of Commerce has not yet responded to requests for comment regarding the filing. As US agencies continue to grapple with balancing national security concerns against the commercial realities of AI development, this case underscores the growing legal friction between regulatory mandates and private sector innovation. If the court rules in Legion’s favor, it could set a precedent for how future government directives affecting foreign access to advanced AI infrastructure are enforced and challenged.