Prohibition of alcohol required the 18th Amendment (ratified in 1919), to give the federal government any authority over the matter.
That authority was revoked by passage of the 21st Amendment (ratified in 1933). So, similar prohibitions regarding marijuana, having nothing to do with actual interstate commerce, must require a constitutional amendment, right?
Well. So one might think, until fast-forwarding less than 10 years into the future. In 1942, SCOTUS ruled that an Ohio farmer named
Roscoe Filburn could rightly be fined 49 cents per bushel of wheat above what the federal government said he was allowed to grow, even though the wheat was grown and consumed entirely on his own farm (as livestock feed and wheat flour for his family). The logic was that by growing his own wheat, he wasn't buying wheat/feed/flour from others, some of which might come from other states, thus affecting interstate commerce and making wheat grown and consumed at home subject to congressional oversight.
Absurd? Yes. Relevance to marijuana laws?
Gonzales v. Raich.
Relying on their absurd ruling in
Wickard, and their slavish dependence upon
stare decisis, the Court compounded their predecessors' previous idiocy by ruling that marijuana grown, sold, and consumed entirely within one state, in accordance with that state's laws, is subject to the interstate commerce clause because it's possible that an out-of-state drug dealer had been deprived of his illegal trade by the medical patient who grew and consumed his own herbal remedy.
The Gun Free School Zones Act relies upon the same tenuous --vaporous, even-- connection to "interstate commerce".
It's time to cast these horrible misinterpretations of the Constitution aside. I don't know how we'll do that, short of hitting the reset button (and I don't think we're at that point, yet).
That makes it all the more maddening: all thinking people can clearly see where SCOTUS is logically wrong, but there's nothing we can do about it.