School officials may conduct searches of students and their belongings if they have reasonable suspicion that the student possesses contraband or violated a rule. This was established in New Jersey v. T.L.O., where the Supreme Court reversed an earlier ruling that a student's purse search violated the Fourth Amendment. Sniffer dogs can be used to detect drugs in lockers and vehicles but cannot sniff students directly. Random drug testing of student athletes has also been upheld as constitutional by the Supreme Court as a means to detect and prevent drug use. Schools must notify students and parents about random search policies through student conduct codes in order to balance safety with protecting civil liberties.