Transcript for 'This Week': Marijuana in Colorado
I stand by my belief, based, I think, on the scientific evidence, that marijuana, for casual users, individual users, is subject to abuse. But as I said in the interview, the incarceration model that we've taken, particularly around marijuana, does not seem to have produced the kinds of results that we've set. President Obama clarifying his recent comments that pot is no more dangerous than alcohol. Coming in the middle of a national debate sparked by the legalization in Colorado and Washington. Our expert panel here to take it on. First we have background from Dr. Richard Besser. Have your I.d.'s ready. Reporter: It's a wild west weed rush. The whole world is watch. Reporter: Lining sparl out the door. It is historic. Reporter: Not just from Colorado. Hollywood, and I'm a teacher. Reporter: The chance to buy marijuana, not just medical, but just for fun. Perfectly legal. Packs of it. Almost Normal. And a huge business opportunity. Can you say anything about how business expanded when it went recreational? On January 1, tripled our sales. Reporter: Tripled. And the second day, January 2, doubled. Reporter: This is the largest dispensary in the state so far. This is the flowering room. And after it's harvested, into the trim room. In here, we dry that finished bud. Reporter: This is a big operation. We are 20,000 square feet and we are expanding into an additional 20,000 square feet. Reporter: Though voters decided, the country is divided. 49% support, and 48% oppose. And Denver's mayor, Michael Hancock, is one of them. You were an outspoken critic of the legalization of marijuana. Right. Reporter: And now you're in charge of making sure it's done right. How do you reconcile that? The people have spoken. And have legalized marijuana in Colorado. My personal views aside, I need to carry forth the regulatory framework and the mechanisms of this industry in a professional and responsible manner. Reporter: This doctor has spent 20 years studying brain addiction in marijuana in teens. It disrupts the development of circuits. And studies show that regular use as an adolescent is associated with a 6-8% reduction in iq. Reporter: High school senior started smoking in the eighth grade. Before school, during school, after school, at night, late at night and woke up in the morning and started all over again. His whole life became unmanageable and he couldn't stop. That's an texas. Reporter: His parents enrolled him here. My recovery. My life. Reporter: A rehab center for teen boys. No one wants to become an addict, it sneaks up on you. Reporter: Over a lifetime, 9% of marijuana smokers will become addicted. But compare that to the addiction rates for other legal drugs. 32% for tobacco, and 15% for alcohol. All the object sieve that it's far less toxic and addictive than alcohol. Reporter: He led the campaign for marijuana in Colorado. If you love alcohol, it should be a slam dunk. No acts of violence and bad behavior. It's bad public policy to steer adults away from marijuana and toward drinking. Reporter: They can test for drinking, for pot -- Nothing on the side of the road that can test like a breathalyzer for marijuana. Reporter: Instead they look for a steady, horizontal gaze, being able to stand on one leg and being able to walk and turn without stumbling. But marijuana arrests aren't just for impaired driving. For in 2011, there were 750,000 arrests for marijuana nationwide, most for possession. We have spent too many resources incarcerating people. Let's be smart, legalize it, tax it, and make sure people are held responsible for the responsible use of it. Reporter: These 22 year Olds came to Colorado to snow board and get high. Legally. What do you think about it being legal? It takes pressure off your shoulders. Reporter: A lot of the pressure. You know the name and the strain. A lot of people are knowing about this product. It's about smell and taste. Flavor, obviously. Reporter: Like a fine wine. Colorado is becoming its own little napa valley.
This transcript has been automatically generated and may not be 100% accurate.