DENVER (AP) — Legal weed in Colorado isn’t hurting its neighboring states. That’s according to a Supreme Court filing Friday that marks the first time Colorado has defended legal marijuana in writing.

Colorado sent the argument to the nation’s highest court as a defense against a lawsuit from Oklahoma and Nebraska, which have asked the court to stop pot regulation.

Colorado says in response that their gripe is with the federal government for not enforcing the Controlled Substances Act. Colorado says that Congress banned marijuana but did not compel states to enforce the ban.

Colorado’s neighbors claim that the 2012 pot legalization vote has sent the drug flooding across Colorado’s borders.

The U.S. Supreme Court has not said whether it will hear the challenge.