High schools often use drug testing as a twofold substance abuse prevention method. In 2013 almost half of high school seniors admitted to using an illegal substance at least once, according to the Monitoring the Future National Survey Results on Drug Use. Administrators use the fear of random testing to deter students, while relying on the actual test to identify teens who already have a problem. Even though the ability to intervene early and help the student to stop using is a plus, legal issues such as privacy and human rights also come into play when it comes to drug testing in schools.

Schools Can't Test Everyone

Random drug testing isn't legal in every school situation. Schools are only legally allowed to randomly test students who take part in competitive sports and clubs, according to the National Institute on Drug Abuse. A student who isn't involved in competitive extracurricular activities is not subject to drug testing, unless there is reasonable cause. That said, if a student has illegal substances or is behaving as if she is under the influence, she can be tested. For example, Mary takes acting classes through a local theater, but isn't part of any sports or other competition-based activities at school. She goes to school regularly, has good grades and never shows any behavioral problems. Mary wouldn't need to fear that the school would randomly test her.

Testing Can Help Athletes

In a study of more than 4,700 high school athletes, 16 percent of students who went to schools that had mandatory drug testing admitted to using substances in the past 30 days. This is in comparison to 22 percent of high schoolers who weren't subject to testing, according to the Institute of Education Sciences. This shows a possible positive effect of drug testing programs as a deterrent to substance use and abuse. The same study also looked at the impact that mandatory drug testing had on the student athlete's decision to participate in school sports. There was no connection between whether the school required drug testing and student's decision to engage in competitive extracurricular activities, notes the Institute of Education Sciences. While mandatory drug testing may stop teens from using illegal substances, it doesn't appear to stop them from participating in sports that require mandatory screenings.

Problems with Reasonable Suspicion

Under federal law, schools can randomly drug test students when there is a reasonable suspicion that the teen is using substances, according to the National Institute on Drug Abuse. Reasonable suspicion may include concrete facts or much more subjective criteria. A teacher, administrator or staff member who sees a student using or possessing drugs has a reasonable cause for requiring a drug test. On the other hand, a teacher can also claim that the student's behavior is erratic or possibly indicative of drug use. The lack of actual evidence means that the teacher's opinion may outweigh what the student has to say. For example, a typically even-tempered student suddenly starts arguing with his teachers and getting aggressive with his peers. Even though this behavior may have many causes -- such as turmoil in a romantic relationship or family problems at home -- the school can demand a drug test.

Inconsistent Federal and State Laws

Although the 2002 U.S. Supreme Court ruling in the Board of Education of Pottawatomie v. Earls allows public schools to drug test middle and high school students who take part in competitive extracurriculars, states may set their own rules. Individual districts must also follow their state's laws when it comes to privacy and student drug testing, according to the American Civil Liberties Union. This muddies the waters about whether drug testing is acceptable or even legal. The inconsistency between federal and state laws is a negative aspect of drug testing. It creates confusion for students, parents and even staffs. It may lead to unnecessary privacy violations or result in families taking legal action. For example, in Pennsylvania, the 2003 Theodore v. Delaware Valley School District ruling trumped the federal laws for drug testing in the state. The state supreme court ruled random testing unconstitutional when it comes to search and seizure laws, notes the ACLU. Parents, educators and administrators need to make themselves aware of how the state's laws stack up to the federal ones before requiring testing.