About a year ago Oklahoma and Nebraska filed a lawsuit against the State of Colorado. The lawsuit alleged that Colorado's marijuana legalization law was harming Oklahoma and Nebraska. Marijuana reformers were quick to point out that Colorado doesn't have a legalization problem - Nebraska and Oklahoma have a prohibition problem. Nonetheless, Oklahoma and Nebraska want the United States Supreme Court to rule on the case. That became a bit tougher when recently the Obama Administration weighed in on the issue, and recommended that the Supreme Court reject the case.
I think that most logical people would see the writing on the wall, and stop pursuing the lawsuit. However, Oklahoma's Attorney General still wants to push forward. Per KRQE:
Oklahoma Attorney General Scott Pruitt has said that he plans to continue to press the U.S. Supreme Court for permission to sue Colorado over its marijuana laws, despite objection from President Obama's administration.
Oklahoma and Nebraska asked for the court's permission a year ago to sue Colorado over aspects of its marijuana legalization plan. A spokesman for Pruitt said that written arguments will be filed next month.
The United States Supreme Court gets to pick and choose which cases it hears. Considering that the Obama Administration, in addition to the State of Colorado, don't support the Court hearing this case, I would imagine the Court will ultimately decide to pass. There are so many worthwhile cases out there to proceed on that I can't fathom why the Court would take up a case that doesn't have much merit to it. In the meantime, I expect Oklahoma's Attorney General to keep barking, but with few people listening to what he has to say.