The National Center on Addiction and Substance Abuse boldly claims that "a child who reaches age twenty-one without smoking, abusing alcohol or using drugs is virtually certain never to do so." Many policy makers and drug abuse professionals do not take the center's claim lightly. In antidrug campaigns and programs, children and adolescents are repeatedly advised to resist the influences of peer pressure, popular music, and films, and to abstain from underage drinking, smoking, and marijuana use.

Efforts are especially aimed at keeping young people from using marijuana due to the "gateway theory" belief that using marijuana increases one's likelihood of using harder drugs. A committee of the American Academy of Pediatrics, for example, claims that "adolescents who use marijuana are 104 times more likely to use cocaine compared with peers who never smoked marijuana," and that "marijuana's role as a 'gateway...