In 1996, a U.S. Department of Health and Human Services (HHS) drug-use survey found that approximately 11 percent of teenagers reported using drugs (primarily marijuana) the previous month, more than double the number from a survey taken four years earlier. During his 1996 presidential campaign, former U.S. senator Bob Dole called this trend “nothing short of a national tragedy,” prompting much analysis of the severity of American teenagers’ drug use.

Many observers agree with Dole’s assessment. Citing a 1996 University of Michigan survey of teenage drug use, the Wall Street Journal stated, “The fact [is] that one-quarter of our 13-year-olds now do drugs.” Some researchers warn that compared with just a few years ago, youths are more tolerant of illegal drugs, want to experiment with more potent substances, and know of more peers who have tried...