This is NOT a 10th Amendment issue. The 10th Amendment applies only to powers not specifically granted to the federal government in the Constitution. It's already been established that the Commerce Clause gives the feds the right to "regulate" virtually anything anywhere any time, inter-state AND intra-state. See Wickard v. Filburn.
What they need to do in MT is establish the state medical market as being separate and distinct from the national/international black market. As long as the feds view all mj commerce as one big market, they can do whatever they want to shut down state mmj programs. Even if mmj commerce is totally within the state, it still affects the national market because it is part of the same market. If the state market is separate, totally contained within the state, and in no way is involved with the black market, then the Commerce Clause does not apply and it becomes a 10th Amendment issue.
I'm not a lawyer, but am available for legal advice if anybody in MT wants a clue.
OH SNAP