State Attorney General Bob Ferguson filed a “friend of the court” brief on Friday in the U.S. Supreme Court urging the court to reject a challenge to Colorado’s marijuana laws.

If the court takes up the case, it could threaten not just Colorado’s law, but also the regulatory structure for marijuana established by Initiative 502 in Washington state, according to a state Attorney General’s Office media release.

Nebraska and Oklahoma filed a lawsuit with the high court in December, claiming that Colorado’s Amendment 64 legalizing marijuana under state law is preempted by federal drug laws. They ask the court to hear the case under its “original jurisdiction” over lawsuits between states. Washington’s brief urges the court to reject that request.

“I am disappointed that Nebraska and Oklahoma took this step to interfere with Colorado’s popularly enacted initiative to legalize marijuana,” Ferguson said in the release. “I filed this brief to protect Washington’s interests and the will of Washington’s voters from interference by other states.

“If the Supreme Court takes the unfortunate step of agreeing to hear this case, it will threaten every state’s ability to make its own decisions about how best to regulate marijuana, whether for medical or recreational purposes.”

The amicus brief argues that the Supreme Court should not take the case based on its own longstanding policies regarding disputes between states. Generally, the court looks at two issues to decide whether to hear such cases: the nature of the case and whether the parties have another avenue to litigate their issues.

This case fails both criteria, Ferguson said.

On the first factor, the Supreme Court usually reserves its original jurisdiction for disputes over states’ sovereign interests, such as competing claims to land or water. This case, by contrast, is a simple policy dispute over how best to regulate marijuana.

The case also can and should be heard first in a lower court. That venue would allow the states to resolve their dispute without immediately impacting other jurisdictions around the country the way a U.S. Supreme Court decision could.

Deputy solicitors general Jay Geck and Alan Copsey and solicitor general Noah Purcell are handling this case on behalf of the Attorney General’s Office.