In T.L.O., the Court held that to be justified, warrantless searches in the school must be based on reasonable grounds at the inception of the search and that the search must be permissible in scope. Cases reviewed by the courts have examined the use of strip searches; sniffer dogs; hand-held metal detectors; and routine searches of students pockets, purses, lockers, and cars. In general, courts have considered most searches permissible when they were not overly intrusive and when there were reasonable grounds to suspect that the student may have violated either the law or the school's rules. Several sophisticated forensic techniques may prove useful in conducting investigations of suspected drug use or weapons possession on the school campus: analysis of hair or nail clippings to identify drug users, the use of metal detectors to identify guns and knives, and the use of laser beams and the Tri-Ess Mini Metal Detector. Other devices include the detectaphone, magnetometers, inspection mirrors, and portable ultraviolet lights -- all noninvasive or nonintrusive search aids that could be used in school searches to combat the problems of drugs and weapons on school grounds. Included are 36 footnotes.