AP Nebraska Attorney General Jon Bruning speaks at a news conference in Lincoln, Neb. on Thursday, Dec. 18, 2014 announcing that he and Oklahoma Attorney General Scott Pruitt are filing a lawsuit in the U.S. Supreme Court seeking a declaration that Colorado's legalization of marijuana violates the U.S. Constitution.

Nebraska and Oklahoma have filed a suit to overturn recreational marijuana laws in Colorado. The neighboring states argue recreational pot is unconstitutional in a suit filed with the US Supreme Court on Thursday.

Specifically, they say Amendment 64, passed by voters in 2012 is against federal law, and federal law trumps state law. And it’s the neighboring states, they argue, that bear the cost of pot diversion out of Colorado in increased arrests.

“Amendment 64 and its resultant statutes and regulations are devoid of safeguards to ensure marijuana cultivated and sold in Colorado is not trafficked to other states, including Plaintiff States,” the lawsuit says. As such, it undermines “Plaintiff States’ own marijuana bans, draining their treasuries, and placing stress on their criminal justice systems.”

Colorado Attorney General John Suthers said the state would fight the lawsuit in court.

“We believe this suit is without merit and we will vigorously defend against it in the U.S. Supreme Court,” he said in a statement.

Marijuana advocate Mason Tvert, who helped lead the campaign to pass Amendment 64, said Nebraska and Oklahoma “are on the wrong side of history.”

“[They] are acting like bullies, and they’ve got no business trying to dictate what Colorado’s marijuana laws should be,” Tvert said.

A marijuana trade group spokesman said that while Colorado’s regulations and enforcement weren’t perfect, seeking to overturn the state’s recreational marijuana laws altogether wasn’t the answer.

“We certainly in Colorado need to be doing everything we can to limit problems in other states,” said Michael Elliot, of the Marijuana Industry Group. “I think we’re certainly willing to partner with them, but this lawsuit is not the right way forward.”

Colorado has 60 days to respond to the lawsuit.