Colorado defended its marijuana laws on Friday against a legal attack from Oklahoma and Nebraska and argued to the U.S. Supreme Court that its sovereignty is being challenged by the two neighboring states.

“Nebraska and Oklahoma filed this case in an attempt to reach across their borders and selectively invalidate state laws with which they disagree,” the Colorado attorney general’s office said in a brief filed with the Supreme Court.

Colorado was responding to a request filed with the high court in December. Oklahoma and Nebraska want the court’s permission to sue Colorado over certain aspects of the state’s laws legalizing the recreational use of marijuana.

The states claim Colorado’s laws allowing the manufacture, possession and distribution of marijuana have led to more illegal drugs being taken across state lines.