In 1983, the Los Angeles Police Department created the D.A.R.E. (Drug Abuse Resistance Education) program to encourage youths to avoid illegal drugs. Today D.A.R.E., which is taught by police officers (primarily to fifth- and sixth-graders) in half of the nation’s school districts, is America’s most prominent school drug-education program.

Advocates of D.A.R.E. credit the program not only for warning children about the dangers of drug use, but for improving youths’ self-esteem and decision-making skills. Robert E. Peterson, director of Michigan’s Office of Drug Control Policy, argues that although D.A.R.E. should not be considered a “magic bullet . . . to prevent drug use,” the program “increases student and parent confidence that they can avoid drugs and deal with peer pressure.”

However, many critics contend...