Greg Toppo:

New research paints a decidedly mixed picture when it comes to mandatory drug testing for high school students trying out for sports or other extracurricular activities: While testing seems to reduce self-reported drug use in the short term, it has virtually no effect on teens’ plans to use drugs in the future.
A U.S. Department of Education study, out today, surveyed students at 36 high schools that got federal grants to do drug testing. Half of the schools had already begun testing for marijuana, amphetamines and other drugs; the other half had not.