"We haven't had an adult conversation about drugs in America," says neuroscientist Carl Hart. The Columbia University academic, known for his experiments tracking the brain activity of drug users, is trying to rectify that state of affairs with his new book, High Price: A Neuroscientist's Journey of Self-Discovery That Challenges Everything You Know About Drugs and Society (HarperCollins).

Hart, an associate professor of psychology, has both a personal and professional perspective on drugs. A former user and dealer, he's a featured character in Eugene Jarecki's anti-drug war documentary The House I Live In, which explores, among other things, Hart's relationship with his son Tobias, who recently served time on a drug charge. Hart's new book, which makes a case for decriminalization, is both a memoir and an exploration of the latest neuroscientific research on drug use.

Hart spoke at reason's Los Angeles office in June about meth, math, violence, and what science can tell us about drug policy. He also took questions from the audience. For video of the event, go to reason.com or scan the QR code on the previous page.

Carl Hart: This book is a hybrid of memoir, science book, and policy. What I'd like to talk about is the science that I've been doing and that other people have been doing with methamphetamine.

Back in 2005 I got a call from the Office of National Drug Control Policy asking me to participate in a roundtable of writers who were interested in writing stories about methamphetamine. They wanted their stories to be more realistic-they were writers for things like Law and Order, CSI, magazines, and so forth. At this roundtable the panelists were a U.S. assistant attorney, an undercover narcotics officer, an adult person who was addicted to methamphetamine, an adolescent who was addicted to methamphetamine, and myself. My role at the panel was to help participants understand where the science was at the time, what we knew from the empirical information.

Basically what I said was that we had tested relatively low oral doses in the laboratory, where we evaluated the effects of those doses of methamphetamine on cognitive performance, mood, heart rate, blood pressure, those sorts of things. My conclusions were that the drug was quite unremarkable. In fact, in people who are well-rested you didn't see much in terms of cognitive disruption, or you didn't see any. Those low doses produce some euphoria, but a moderate range of euphoria.

When I finished my presentation my fellow panelists were horrified. They were horrified because they had told stories about the horrors of methamphetamine that they saw in the natural ecology. They recounted stories of methamphetamine users developing superhuman strength. When someone was on methamphetamine, it was said, you had to increase the caliber of weapon; regular Tasers no longer worked with these individuals. Another story that was recounted was that methamphetamine was like no other drug that law enforcement had ever seen. This particular cop said he had more than twentysomething years experience on the force and had never seen anything like methamphetamine-and he had seen crack users and that sort of thing. This drug methamphetamine, he claimed, exerted unique pharmacological effects. Finally, when I challenged some of the claims that were being made, he turned to me and said: "Dr. Hart, when you see a parent cut the head of their child off and throw it at you then maybe perhaps you will become a believer."

I tried to explain that these types of stories, these anecdotes-particularly about drugs-weren't new. We had heard them before. The stories about drug users developing superhuman strength, the stories about some new drug being like no other drug we've ever seen, and the stories about drugs causing this sort of wide range of cognitive disruption.

What I'd like to do is evaluate these three sorts of claims that seem to be pervasive in our history when it comes to drugs.

The first [is] these individuals developing superhuman strength. If you go back to The New York Times, for example, on February 8, 1914, what you find is a huge editorial: "Negro Cocaine Fiends Are New Southern Menace." In this piece the author argued that black people, when they have cocaine, they develop superhuman strength. So much so that southern police forces had to increase the caliber of their weapons. They moved from the .32 caliber weapon to the .38 caliber weapon because the .32 caliber weapon or bullets didn't affect black people on cocaine.

I know it sounds comical, but this was actually believed. And these things come back in new forms. Maybe a year and a half ago, two years ago, we heard about the guy in Miami who chewed the face off of another guy. It was said that the person was on bath salts and that bath salts cause such extreme effects that you get this kind of behavior. But when the toxicology was in, there were no bath salts in this person's system. The only thing that was in the person's system was THC, and we don't know when was the last time this person used THC. It could have been weeks.

The point is that these arguments, these claims, they are recycled generation after generation. And we laugh at some of them because of the language, but the language is tempered to fit the contemporary folk. It doesn't seem so outrageous if you're not a critical thinker. But of course most of these claims are just exaggeration.

The [second] claim is that methamphetamine produces unique cognitive effects. What I did, along with my Ph.D. student at the time, Matt Kirkpatrick, is that we ran a study in which we gave research participants-of course we passed all of the ethical requirements-intranasal methamphetamine at a low dose and a large dose on one day. It's all under blind conditions. We also gave participants dextroamphetamine, the active ingredient in Adderall, on other days. Of course a placebo was included.

We evaluated the effects of these drugs to see whether or not methamphetamine was unique compared to just regular amphetamine, because when you look at the chemical structure of these drugs, they look almost identical excepting for the meth group, which is on the methamphetamine structure. What we found was that the drugs produced nearly identical effects. They are the same drug. Methamphetamine is the same drug as the active ingredient in Adderall. The notion that methamphetamine produces unique effects is just simply not supported by evidence.

Finally I was interested in this notion that methamphetamine causes all of these cognitive disruptions. If you all have been paying attention in the country for the past 5 to 10 years you might know something about the Montana Meth Project, in which they make these slick advertisements-which they call "education"-about the dangers of methamphetamine. Oftentimes these advertisements indicate that methamphetamine causes widespread cognitive disruptions. And it seemed as though the scientific literature was in support of what was being said in these advertisements.

In 2012, I published a review of all the scientific literature that was relevant for cognitive performance and for brain imaging. What I concluded was the interpretations in the scientific literature were wildly overstated in terms of the effects of methamphetamine on cognition, in terms of the effects of methamphetamine on brain structure. My paper was published in Neuropsychopharmacology in 2012.

So given that our drug policy is based on these faulty assumptions, one of the things that I call for in High Price is that we should rethink and reevaluate how we are regulating drugs like methamphetamine, drugs like heroin, drugs like cocaine, and so forth. And the main reason I call for this reevaluation is this: Each year in this country we arrest 1.5 million people for drug-related violations. More than 80 percent of them are for simple possession. If our assumptions that these drugs are so dangerous that we have to go after them with such ferocity are faulty, I think that we could decrease the blemishes that we put on people's records by decriminalizing drugs rather than the approach that we're taking.

When you call for decriminalization in this country you have to provide some education, because the country is quite ignorant about drug policy, about drugs in general. Decriminalization is not legalization. Legalization is what we're doing with alcohol. If you're 21 or older, you can purchase alcohol without fear of being prosecuted. You can sell alcohol legally. With decriminalization, you cannot sell drugs. They still remain illegal. Possession also remains illegal, but you can no longer get a criminal record from possessing a drug. Instead it would be treated like we treat traffic violations. That way we decrease the likelihood of putting blemishes on people's records and enhance the likelihood that they will be able to get jobs and contribute to society. When we think about the guys who have occupied the White House-President Obama, President Bush, President Clinton-all three of those guys used illegal drugs in their youth. If they would have been caught, they would've gotten felony charges and probably would not have been allowed to make the contributions that they have made to our country.

One of the things that happens in this discussion is that experts are very comfortable talking on areas in which they have limited expertise. I'm not one of them, and I have limited expertise in markets. My expertise is the effects of drugs on people. But what I can tell you is why I favor decriminalization rather than legalization: Legalization will provide the opportunity for people to exaggerate the extent of the harms caused by drugs. I know that for a fact. Because the country is so ignorant about what drugs actually do, we should decriminalize and then have a corresponding increase in education about these drugs. Realistic education.

Since I've been talking about methamphetamine: Methamphetamine causes people to have to have increased heart rate, blood pressure, and so forth. The number one killer in the United States is heart disease. So if you have cardiac issues, the public health message will be blared: "Don't take methamphetamine!" Another issue is that methamphetamine is outstanding at keeping people awake. Chronic sleep loss associated with all kinds of cancers, associated with psychiatric illness, the public health message would be: "Please don't take methamphetamine near bedtime! Get sleep!" This is realistic education to help people. That's why my focus has been on decriminalization rather than legalization. I think the country's too ignorant, we haven't had an adult conversation about drugs, and I'm trying to do that with High Price.

reason: Are all these stories just totally fabricated out of thin air? Because I recall way back when it was "demon weed" about marijuana and "devil rum."

Hart: I don't want to leave you with the impression that psychoactive drugs don't have potentially powerful mind-altering effects. Because they do.

[But] in many of the stories told about those drugs like marijuana in the 1930s, the demon rum, and that sort of thing, drugs serve as convenient tools to further demonize groups that we don't like. We associated marijuana with those Mexicans who are taking jobs from the good folks in Texas. Black folks are taking jobs from white folks in the South, we don't like them. So we associate drugs that are not used widely in the society with a specific despised group.

Today it's a hell of a lot more difficult to demonize marijuana as we once did. Fast-forward to the 1980s. A number of people had used powdered cocaine. Hollywood was really supporting that industry. But there was not the same number of people using crack cocaine. So now you can say: This is a new form of cocaine. It's not the cocaine that you're using, my man. This is a new form. And so it becomes associated with these people, even though black people didn't use crack cocaine at higher rates than white folks. But certainly based on the media portrayal it was easier to get that impression.

Methamphetamine today is associated with despised groups. "Poor white trash." Gay folks. That sort of thing. A relatively small number of people use methamphetamine so you can vilify those groups. But it's a hell of a lot more difficult to vilify marijuana today.

reason: What does the data show on addiction? Would decriminalization help that process of getting off of addiction? Or is addiction exaggerated in general?

Hart: The vast majority of people who use these substances are not addicted. Maybe 10 to 20 percent are, but 80 to 90 percent are not. Most of our attention, when we talk about these drugs, is focused on the small pathological group. I focus more on the 80 to 90 percent.

I hope that we would redistribute the money that law enforcement currently gets. We spend $26 billion a year on dealing with this drug problem. If we redistribute the money into treatment and treatment research it would enhance treatment. We currently have some pretty good treatments to treat substance abuse. It's just that we also have a lot of quacks out there.

We also have to realize that, like law enforcement, the treatment industry has a stake in our current approach. It's either jail or treatment. [But that] doesn't make any sense when the vast majority of people don't need either.

reason: Does the government make it difficult for people to study illegal drugs?

Hart: I sit on a number of review committees and one of the things we want to make sure before people get approval to study these drugs is that they have the appropriate amount of experience to do this research, and to make sure that they have the appropriate safeguards in place. Because you can imagine if you had people do this kind of research and they don't have the experience and they don't have the appropriate safeguards: If someone gets hurt you can imagine how that will set back the scientific investigation into this study. Think about Timothy Leary. His antics set back the research into hallucinogens 40 years. We don't want to see that happen again.

reason: Is there any study that has ever shown that any of these substances force people to do bad things-violence, crimes, and so on?

Hart: We have been doing this research for decades in which we bring people into the lab and administer drugs in order to develop better treatments, in order to determine the effects of drugs on people for a wide range of reasons. We've given drugs like heroin, methamphetamine, crack cocaine, marijuana, you name it. Alcohol. We've given thousands of doses of these drugs, but we haven't seen any violence in the context in which we give these drugs.

That's not to say that people who use drugs don't get violent sometimes. You might see some violence with some of these drugs, but it's certainly not because of the pharmacology of the drugs. When we have this kind of discussion we sometimes think: If one person gets violent on crack cocaine, that's enough to change the policy. That's ridiculous.

The notion that we can prevent every accident, every sort of bad thing from happening in a society-if people have that notion they probably shouldn't be allowed to talk to the public.