The brief, filed March 10 in San Francisco, argues that a temporary restraining order blocking enforcement of the Pentagon's “supply chain risk” designation would serve the public interest.
The brief highlights a procedural contradiction that has received little attention in mainstream coverage: The Department of Defense gave itself a six-month phase-out period to transition away from Anthropic's tools, but applied the designation to contractors immediately with no equivalent runway.
Microsoft's lawyers called this out directly, noting that tech suppliers must now scramble to audit, re-engineer, and reprocure products on a timeline the government didn't impose on itself.
Microsoft also raised an alarm that cuts to the heart of the legal dispute. The supply chain risk authority invoked—10 U.S.C. § 3252—has historically been reserved for foreign adversaries. Only one such designation has ever been issued publicly under related statutes, and that was against Acronis AG, a Swiss software firm with Russian ties. Using it against a San Francisco AI startup is, as Microsoft put it, “unprecedented.”
The brief's most pointed argument is structural. If a contract dispute between one agency and one company can trigger a national-security blacklist, then every company doing business with the federal government just inherited a new category of existential risk. Microsoft's lawyers described an industry model built on interconnected services, where one banned component can freeze entire product lines.
Here is re-post of an internal post:
We have been working with the DoW to make some additions in our agreement to make our principles very clear.
1. We are going to amend our deal to add this language, in addition to everything else:
"• Consistent with applicable laws,…
The brief stops short of endorsing Anthropic's specific AI safety positions on autonomous weapons and mass surveillance—the two red lines that triggered the standoff. Instead, it frames the case in terms any government contractor can understand: due process, orderly transitions, and the effects of weaponizing procurement law over policy disagreements.
Microsoft’s request is a temporary restraining order, not a verdict. The tech giant wants the clock slowed down enough for the parties to negotiate—and for its own products to stay legally deployable while they do.
