The term "zero tolerance" refers to government and private employer policies that require specific consequences or punishments for certain offenses. Most public schools now have zero-tolerance policies for firearms, weapons other than firearms, alcohol, drugs, and tobacco. Generally, zero-tolerance policies are rigid, requiring harsh punishments for any level of improper behavior, with no room for explanations or excuses. The courts have endorsed drug-testing programs that allow employers to enforce zero-tolerance policies.

Zero tolerance is also a general attitude toward drug use. According to this perspective, the use of any amount of illegal drugs is harmful to the individual and society, and the goal of drug policy should be to prohibit any and all illegal drug use. A contrasting viewpoint holds that not all drug use is equally harmful. According to this view, occasional use of drugs should be viewed as something different from and less serious...