Just weeks before the one-year anniversary of legal marijuana in Colorado, the state's status as breaker of the green ceiling is under assault from an unlikely source: its neighbors. On Thursday, Oklahoma Attorney General Scott Pruitt announced that his state was teaming up with Nebraska to petition the Supreme Court to declare legal marijuana in Colorado "unconstitutional."

Fundamentally, Oklahoma and states surrounding Colorado are being impacted by Colorado’s decision to legalize and promote the commercialization of marijuana.

Their main gripe is that weed is wending its way into their states from Colorado, which neighbors both Oklahoma and Nebraska. Marijuana is still illegal at the federal level although earlier this week, Congress formally ended the federal ban on medical marijuana.

This lawsuit has set off a regional war between the top lawyers in the states. Colorado Attorney General John Suthers responded by saying the initiative is "without merit" and that Colorado would fight the suit in the Supreme Court.

Morgan Fox, who manages communications for the Marijuana Policy Project, brushed off the lawsuit. He helped to shepherd Colorado's legalization effort in 2012.

"Marijuana was widely available in Nebraska and Oklahoma well before Colorado made it legal," he said, adding that "it would continue to be available even if Colorado were to all of sudden make it illegal again." Fox also noted that if the lawsuit were successful "it would only make regulation [of marijuana] in Colorado illegal. Marijuana possession would still be legal."