In Canada, cannabis is legal now. From what I hear, it's still illegal in the States.
Years ago, it was soooooo illegal that people went to prison for a very long time simply because they had some in their pockets. Scientists could not study the plant or the chemicals thereof because it was such a terrible, heinous chemical.
Years ago, it was soooooo illegal to discuss real orbital mechanics about the Earth and the Sun that a very learned Italian guy was almost killed because he was studying it all and telling people what he knew.
Have you ever read anything about Masters and Johnson and their studies? Quite a shock to the established ideas of sex, eh?