Many schools employ drug testing to deter students from using illegal substances – but new research has revealed that these checkups actually fail to dissuade teens from trying drugs.

According to Counsel and Heal, approximately 20 percent of high schools in the United States utilize drug testing, usually to screen students participating in sports or after-school clubs.

In a new study published in Journal of Studies on Alcohol and Drugs, researchers interviewed 361 students – a third of whom reported having a drug policy at school. Through these reports, the scientists said they did not find any evidence that drug testing successfully prevented students from trying drugs. They noted that students from schools with drug testing were just as likely to try illegal substances as students from schools without drug testing.

"Even though drug testing sounds good, based on the science, it's not working," said study author Daniel Romer, of the University of Pennsylvania Annenberg Public Policy Center in Philadelphia. "So as a prevention effort, school drug testing is kind of wrong-headed."

However, the researchers did find an effect drug deterrent for students. They discovered that a positive school environment – one with clear rules and good student-teacher relationships – helped to prevent teenagers from using drugs. Students enrolled in schools with a positive climate were 20 percent less likely to use marijuana and 15 percent likely to smoke cigarettes.

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