Breath mints won't cut it anymore for students who have been smoking in the bathroom.
Some schools around the country are administering urine tests to teens to find out whether they have been using tobacco.
Opponents say such testing violates students' rights, but some advocates say smoking is a ticket to more serious drug use.
Testing students for drugs got a boost in June when the U.S. Supreme Court affirmed random testing of those in extracurricular activities. Tobacco can easily be added to the usual battery of tests.
Schools in pockets of Alabama, Indiana, Texas and Florida are among those testing students for smoking or chewing tobacco or dipping snuff.