Lindsay Earls wanted to offer her voice and musical talent to Tecumseh High School's choir and its marching band. But first, she had to offer a urine sample.

In 1998, her school district asked students who engaged in extracurricular activities from seventh through 12th grades to consent to drug testing.

"It was sort of sprung on us," said Earls, now a freshman at Dartmouth College. "I felt strongly about it. That is none of their business."

Her lawsuit before the U.S. Supreme Court on Tuesday could help decide whether school districts can require drug tests for students who want to participate in after-school activities from cheerleading to chess squad.

At issue is whether the Fourth Amendment right against unreasonable searches allows drug tests without evidence that the student or the school has a drug problem.

"It's basically a misdirected policy," said Graham Boyd, an attorney for the American Civil Liberties Union who represents Tecumseh School District students who challenged the district's random drug-testing policy.

"The most effective way to keep students from using drugs is to engage them in after-school activities," Boyd said. "The last thing you want to do is to put up barriers to these activities."

Supporters argue that testing deters illegal drug use by students before it becomes a problem.

"We don't think you should have to have a disaster on your hands before you do something to stop it," said David G. Evans of the Drug-Free Schools Coalition.

"This is really all about protecting kids. It gives kids a chance to say no."

At Tecumseh High School, only students involved in competitive extracurricular activities were tested on the theory that by voluntarily representing the school, they had opened themselves to greater scrutiny than other students.

Earls said she provided urine samples for testing two or three times. All of the tests came back negative.

Overall, 505 high school students were tested for drug use. Three students, all of them athletes, tested positive, Boyd said. Two of the athletes also participated in other extracurricular activities.

The school offered drug counseling after a positive test, and those who complied could remain on their teams. Those who refused were barred from competition.

In 1995, the Supreme Court ruled that a school district in Vernonia, Ore., could require drug testing for students involved in athletic competition.

"When courts have upheld blanket drug-testing, it has been based on some dangerous activity" like sports, Boyd said. "There's nothing about singing in the choir that poses any danger."

Earls, her sister, Lacey Earls, and a third student, Daniel James, sued the school district in federal court alleging that the policy violated their Fourth Amendment rights.

A district judge in Oklahoma City upheld the policy, ruling that the intrusion into the students' privacy interests was minimal considering the devastating effect of illegal drug use on children.

But the decision was overturned by the 10th U.S. Circuit Court of Appeals in Denver, which said it is generally unconstitutional for public schools to require students in non-athletic extracurricular activities to be tested for illegal drugs.

Legal papers filed by Tecumseh's attorney, Linda Meoli of The Center for Education Law in Oklahoma City, said a student drug problem has existed in the district since at least the 1970s.

But Marsha Levick, legal director of the Juvenile Law Center in Philadelphia, said there is not much evidence of drug use in Tecumseh, about 30 miles southeast of Oklahoma City.

"It's very minor and very trivial and very episodic," she said.