The initial hurdle is whether the case will even be heard. The last state v state case was not! It involved a claim that Colorado's lack of control of ts legalization of marijuana was harming neighboring states. By a 7-2 vote the appeal was simply declined. However, three of the justices who voted to decline have been replaced. On the other hand, Scalia was on the side of the declining justices. Of course, vote integrity is a little more important than getting stoned... for most people.
Link: https://www.nytimes.com/2016/03/22/us/politics/supreme-court-declines-to-hear-challenge-to-colorados-marijuana-laws.html