Forget medical uses. Marijuana is a naturally occurring plant. It requires no processing to use it, other than lighting it on fire. Keeping a law on the books that makes a plant illegal is beyond asinine.
It should have never been illegal in the first place. It was only made illegal because the cotton farmers knew hemp would put them out of business. It had absolutely nothing to do with the effects from smoking it.
It is the reason millions of Americans have gone to jail. Those people are in jail, not working, not being parents, and not participating in society all because of a plant.
It causes massive loss of life and untold other crimes due to the cartels and related human and drug trafficking.
And if it were legal, it would provide a massive tax windfall and a boost to our economy. Any of those are enough reason to make it legal, and why the vast majority of Americans support legalization.
Do not forget about the original individuals behind the "reefer madness" B.S. and prohibition in the first place, William Randolph Hearst (timber/paper tycoon) and Harry Anslinger (first commissioner of the Federal Bureau of Narcotics). Hearst worked with Anslinger to make sure that marijuana was made illegal by law. Also for the record, Anslinger was a known racist FWIW as well.