Drug prohibition has led to such hysteria about drug use that some schools -- thankfully only less than 5% of the total in the U.S. -- drug test students. Drug policy reformers have said for years this plan wouldn't work, and now a U.S. Department of Education study shows that mandatory drug testing for high school students has no effect on teens' plans to use drugs in the future. About one in three students said they "probably" or "definitely" will use drugs in the next year.