[Kemal]

I don't mess with either, but I think that as a matter of personal liberty, marijuana should be legal.

The history of why certain drugs became illegal in the U.S. is long and tortured. It happened over a period of several decades. There was a time when products containing cocaine and opium were sold over the counter. They were sold as cures for a variety of ailments. During the progressive era of the early 20th century drugs became more regulated, first at the state level, then at the federal level. At first it was more about "truth in advertising" - forcing companies to label the ingredients of their products and that sort of thing. There was a time when you could still these drugs with a doctor's prescription.

During the 1910's and 20's various laws effectively outlawed cocaine and opiates(heroin, etc.). Racism against blacks and hispanics played a role in the passage of these laws.

And everyone knows about prohibition, of course. Note that alcohol prohibition (1919-1933) in the US required a constitutional amendment. There is no similar constitutional amendment authorizing the government to prohibit drugs like marijuana. It's all justified under the government's power to tax and the power to regulate interstate commerce. The first federal anti-marijuana law was the Marijuana Tax Act passed in 1937. It didn't outlaw marijuana per se, because you could technically possess it if you paid the government a special tax for a permit. But the government simply didn't issue any permits. (I think some clever dealer actually had one issued to him once somehow, but I don't remember the story.)

The other authority comes from the interstate commerce power. According to the government, damn near everything affects interstate commerce these days. In the medical marijuana case before the court now one of the issues is: does the government's power to regulate interstate commerce extend to people who grow marijuana for personal use, if the marijuana doesn't move interstate and isn't sold? The government's lawyers argue yes, because the production of marijuana increases demand, and that will lead in interstate commerce in marijuana. Personally I think the prosecutors in this case are full of shit and they should be out locking up terrorists, not sick people.