Interstate Commerce laws would prevail. Case in point, garbage and hazardous waste disposal from the source states were banned by several states for ultimate disposal or final deposition or treatment in their own state borders. Private companies affected by the rulings were able to overturn the bans because of interstate Commerce laws allowing free enterprise to take place.

In my view, this would apply to legal marijuana states and illegal marijuana states, too. I believe it will ultimately be decided that transporting marijuana and marijuana associated goods and services across borders will be allowed. It will be decided at the federal level.