This context is not really an area of expertise, so maybe someone will correct me.
I think you're confusing two things: the prohibition of marihuana, which iirc happened in america in the first half off the 20th century (late 20's begin 30's I believe) and the war on drugs which indeed happened begin 70's under conservative influence (Nixon)
Underneath I have linked a famous book, outsiders. It's the opinion of Howard becker a sociologist/ criminologist who was a marihuana user himself. He argued that the prohibition of marihuana led to a people seeing other people as deviants (without actually having committed something that was previously considered an offense). Basically he lay the roots of the deviance as a social construct.
This is only one opinion. I can't tell you if it's the consensus opinion or not, if there already was something as a consensus opinion maongst scholars on this topic. I hope someone else can answer this.