Random drug testing in schools really doesn't prompt youths to say no to drugs, new research says.

Despite long-standing public campaigns, in which schools across the nation have asserted tests make it easier for students to avoid illegal drug use, a recent survey of high school students found a positive school environment was more successful in helping students avoid alcohol, cigarettes and marijuana than the threat of random testing .

The research was published Jan. 13 in the Journal of Studies on Alcohol and Drugs.

Researchers from the University of Pennsylvania's Annenberg Public Policy Center interviewed 361 high school students across the country who participated in a more general National Annenberg Survey of Youth back in 2008.

Researchers followed up the drug-related questioning about 12 months after their initial inquiries and asked participants whether they had used alcohol, cigarettes or pot.

The study determined students were about 20 percent less likely to smoke pot and 15 percent less likely to puff on a cigarette if they generally felt their schools were positive places. The trend was not affected by changing demographic or geographic factors.

Study author Dan Romer, director of Annenberg's Adolescent Communication Institute, told the media he wasn't surprised by the results, because in a school with a positive environment, students will be more responsive to what teachers say.

Students, Romer continued, need to understand why their schools have set certain behavioral and disciplinary policies.

A school that has a positive climate might also implement drug testing, he said, since the two strategies aren't mutually exclusive.

However, the new research notes that if school administrators are truly concerned about substance abuse, they may want to engage students in programs that promote more respectful school climates before any drug testing.

Supporters of random drug testing say it can serve as a deterrent, as well as a way to identify students who need more support.

The Supreme Court upheld the constitutionality of the practice, in 1995 and again 2002. But those ruling also limited the use of testing to students involved with competitive extracurricular activities.