A lot of addiction actually ends by age 30 - something like 50 percent of all addictions with the exception of tobacco - and I think a lot of what's going on there is that the self-control areas of the brain are finally developed enough to be able to stop yourself from relapsing or just continuing. There is a maturational aspect to it as well.

Marijuana is not not harmful, but is the least harmful psychoactive substance that we have, with the possible exception of caffeine.

Incarceration is as useful for addiction as it is for diabetes - i.e., not useful and potentially harmful, particularly for kids.

Because addiction is a developmental problem, the developmental stage is important, things like employment are important, things like having a sense of purpose, meaning and hope are important, and this is why there's been so many spiritual cures for addiction, because those things often give people a sense of meaning and purpose.

There's traditionally been two different ways of seeing addiction. Either it's a sin and you're a horrible bad person and you are just choosing to be hedonist or it's a chronic progressive disease. And while I certainly believe addiction is a medical problem that should be dealt with by the health system, the way we've conceptualized addiction as a disease is not actually accurate, and it has unfortunately become stigmatizing and it's also created a lot of hopelessness in a lot of people.

When President Nixon declared war on drugs on June 17, 1971, about 110 people per 100,000 in the population were incarcerated. Today, we have 2-3 million prisoners: 743 people per 100,000 in the population. The U.S. has 5% of the world's population, but 25% of its prisoners. As Senator Jim Webb once put it, Either we are home to the most evil people on earth or we are doing something different and vastly counterproductive.

I know that sounds really extreme, but if you just look at the history, you will find Harry Anslinger [first U.S. commissioner of the Bureau of Narcotics] going on about satanic swing and how reefer will make black people think they're as good as white people - which to him, obviously, was a very horrible outcome. This is the basis of our drug laws.