A CNN article quotes John Ehrlichman:

“The Nixon campaign in 1968, and the Nixon White House after that, had two enemies: the antiwar left and black people,” former Nixon domestic policy chief John Ehrlichman told Harper’s writer Dan Baum for the April cover story published Tuesday.
“You understand what I’m saying? We knew we couldn’t make it illegal to be either against the war or black, but by getting the public to associate the hippies with marijuana and blacks with heroin. And then criminalizing both heavily, we could disrupt those communities,” Ehrlichman said. “We could arrest their leaders. raid their homes, break up their meetings, and vilify them night after night on the evening news. Did we know we were lying about the drugs? Of course we did.”
My Thoughts
I’ve never been a drug user and as a social worker I’ve seen first hand the damage drug abuse does to families and especially children.  So, I am not particularly sympathetic to the efforts to glamorize drug use in magazines like The Rolling Stone.  However, it is abundantly clear that the War on Drugs has been a colossal failure not only wasting billions of dollars but causing incalculable “collateral damage.”
I also think of myself as being cynical of almost everything; but, never had it dawned on me that the War on Drugs had never been about limiting the damage done by drug abuse. This new piece of information from one of the few people who absolutely know the truth about this issue is both disturbing and will require a great deal of thought.