You know what, though? That there are competing laws strengthens the case against the feds. Any state law passed that challenges the federal prohibition on marijuana ultimately weakens their control on that area of law. The federal courts will, of course, assert otherwise, but now those states have a vested interest in challenging federal jurisdiction. This is good. It might be messy, but this is good. When was the last time states had a vested interest in challenge federal jurisdiction where the feds claim to have complete control of the field?