Though states such as Colorado and Washington are easing up on marijuana, the war on drugs is still in full force throughout the U.S.

As part of the drug war, many high schools across the country test students for drugs. New research, however, shows that such programs are not only not effective, but could have the opposite of their intended effect on students.

A new study published in this month’s issue of the Journal of Studies on Alcohol and Drugs shows that students in the around 20% of U.S. high schools that drug test students are just as likely as other students to try marijuana, smoke cigarettes, or consumer alcohol.

“Even though drug testing sounds good, based on the science, it’s not working,” said Daniel Romer, a co-author of the study and a pubic policy researcher at the University of Pennsylvania. “So as a prevention effort, school drug testing is kind of wrong-headed.”

According to Romer, the best that parents and school officials can hope for with drug testing programs is that students stay away from commonly-tested-for drugs such as marijuana. Meanwhile, the atmosphere of suspicion such programs create might be the opposite of what actually works to keep kids off drugs.

According to the study, a “positive climate” at schools is what works best to keep student away from drugs. The study’s authors say that cultivating such a climate involves mutual respect between teachers and students and “clear rules.” Students in such schools were found to be around 20% less likely to try marijuana and 15% less likely to smoke cigarettes. Positive school climates were not seen to have an effect on students’ alcohol consumption.