Marijuana is the most widely used illicit drug in Amer- ica. Some 40% of the adult population has tried mari- juana at least once. It is the third largest agricultural commodity in the nation and a $10 billion industry. In many areas of the country, marijuana production or sale is the largest moneymaker by far. In Florida, for ex- ample, it ranks ahead of every business except tourism. It is also a widely misunderstood substance. An en- tire generation...