http://www.huffingtonpost.com/judge-frederic-block/war-on-dr...
It surely isn't simply based on race as your hippie example points out: Rather, any group that was or is 'bad' at the time, be it based on race or status (being poor, for example). Not all race and class, but lots of it.
And that makes things a bit fuzzy, unfortunately. Much harder to prove racist policies. And you wind up having to do a lot more digging and use examples. Think of the stereotypical crack dealer: That's from the 90's, if I remember correctly. We know the drug policies disproportionately affect minority communities and poor folks, yet numbers also tell us that addiction hits most levels of society. And have failed to change it. We didn't erase the racist-inspired laws either. To me, this sort of thing all stinks of. And I'm too cynical to think that suddenly, race had nothing to do with it.
Unfortunately, this sort of thing does little to prove any of it to a non-believer.
You see, I believe your point, but that won't convince those who believe it wasn't influenced by racism. They'll say "conspiracy theory" and move on.
Disregarding cannabis, it also seemed to me that LSD was to become illegal to harass the hippie community. But how to prove this?
The way this works appears to be rather easy; you look at the characteristics of your political opponents, and then decide what they have in common which your status quo group doesn't. Then a process is begun to incite FUD. Once that campaign in successful you got momentum in your group and you make a law which makes that thing illegal.