Many schools employ drug testing to deter illegal substance use by students, but new research from Counsel and Heal has revealed that these checks fail to dissuade teens from trying drugs, Fox News reports.

According to the study, published in the Journal of Studies on Alcohol and Drugs, approximately 20 percent of high schools in the U.S. use drug testing, usually to screen students participating in sports or after-school clubs. However, the researchers said they did not find any evidence that drug testing successfully prevented students from trying illegal drugs, and they noted that students from schools with drug testing were just as likely to try illegal substances as students from schools without it.

The researchers did find, however, that a positive school environment with clear rules and good student-teacher relationships helped to prevent teenagers from using drugs. According to the report, students enrolled in schools with a positive climate were 20 percent less likely to use marijuana and 15 percent less likely to smoke cigarettes.