If you grew up scared of what illicit drugs could do to you — hearing about all the horrors that could befall you from everyone from Nancy Reagan to your parents — the threat may have felt very real: If you actually took a puff off that joint that the kid who slept through math class offered you, it could lead to failed relationships, chronic unemployment, self-destruction.

The shame would outlive you.

But drugs are a more complicated matter than they’ve been made out to be, according to Dr. Carl L. Hart. In his new book Drug Use for Grown-Ups, the Columbia University professor of psychology and psychiatry zealously argues that drug use should be a matter of personal choice — and that, in more cases than not, personal choice can lead to positive outcomes. His positions may seem quite extreme to some but they also, by and large, make a lot of sense — and are backed up by ample research.

A major reason drugs have such a negative public image, Hart asserts, is racism. He notes that after the Civil War, some Chinese railroad construction workers smoked opium and, sometimes, established “opium dens” to do so. Over time, more and more white Americans visited these dens to smoke opium too. That in turn led to broader, bigoted social fear among whites, like, for example, the sentiments captured in H.H. Kane’s 1882 report:

Then there was the post-Civil War use of cocaine among some Black day laborers, something Hart writes was at first encouraged by white employers because of the productivity it could promote. Soon enough, however, articles appeared widely that tried to make a connection between African American cocaine use and criminality. One particularly egregious article in The New York Times in 1914, cited by Hart, even reported that some police in the South “who appreciate the vitality of the cocaine-crazed” were switching to higher-caliber weaponry capable of “greater shocking power for the express purpose of combating ‘the fiend’.”

But horrifying history aside, one of the book’s most eye-opening aspects is its challenge of the long-running association between drugs and addiction. First the basics: Addiction, according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM – 5), must be a source of distress for a drug user. It must also interfere with a person’s job, parenting or personal relationships. Other indications of addiction may be high tolerance, withdrawal symptoms, or persistence in repeated failed efforts to quit. Hart writes that 70 percent or more of drug users do not meet this criteria for addiction. In fact, he notes “such issues affect only 10 percent to 30 percent of those who use even the most stigmatized drugs, such as heroin or methamphetamine.”

Hart argues, citing much evidence, that it’s a pre-existing kind of personal vulnerability — psychological and/or circumstantial — that precedes the drugs themselves that can lead to addiction. He asserts that:

Hart notes that “people stayed in treatment. The number of new blood-borne infections, such as HIV and hepatitis C, dramatically decreased. Petty crimes committed by heroin users also went down. And no heroin user has ever died while receiving heroin in the clinic.”

For those concerned with the efficacy of such programs, the Swiss approach to treating heroin addiction was also taken up by other countries like Belgium, the Netherlands, Denmark, and Germany after programs based on abstinence or methadone treatment failed. And Hart answers the inevitable question many will pose about the alleged connection between drugs and poverty and crime. He thinks back to his youth when even he didn’t see things the way he does now.

“What about the notion that drugs led to poverty and crime in my neighborhood?” he asks. “Well, that is simply an ugly fantasy, an incredibly effective one to be sure. It’s effective not only because it is still believed by large segments of the American public but also because it seemingly provides a simple solution to complicated problems faced by poor and desperate people. Many other complex factors are responsible for the turmoil seen in the places of my youth and other communities. But it took me a long time to see that clearly myself.”

Hart also offers as an alternative to the punitive approach to drug use America has historically taken. Broadly, he advocates for drug legalization because he sees it as everyone’s right to take whatever drug they want. But he also so importantly emphasizes that anti-drug laws have disproportionately ruined the lives of people of color; for more detail on that, this Human Rights Watch report offers data.

Drug Use for Grown-Ups makes the case for people having the right to use drugs if they want to. As Hart sees it, it would be best for drugs to be legal, in tandem with government regulation, purity testing, and social support for those who need it. What we have now, instead, is racist mass incarceration and social shame prevailing (and drugs hardly scarce anyway).

This, understandably, he does not see as sustainable, nor morally justifiable, nor effective in any way. He persuasively argues for us, as Americans, to chart a more humane course for how we see drugs in our society — a course rooted in personal freedom without social stigma.