The plaintiff, Abigail Noel Fisher, 18, lives in Richmond, southwest of Houston, and attends Stephen F. Austin High School in nearby Sugar Land. Despite ranking in the top 12 percent of her class, scoring 1180 out of a possible 1600 on the SAT, and playing the cello, she was rejected last month by UT, says the lawsuit, which was filed in U.S. District Court in Austin.

UT and other public universities in Texas are required by state law to accept any student from Texas who ranks in the top 10 percent of his or her high school. UT considers race and ethnicity, among other factors, in deciding whether to admit other students as part of its effort to boost enrollment of Hispanics and blacks.

"But for her race and ethnicity, it is our belief she would have been admitted to the University of Texas," said Edward Blum, director of the Project on Fair Representation, a legal-defense group that fights the use of race and ethnicity in public policy.

The group, based in Washington, is underwriting part of the litigation costs, and Fisher's lawyer, Bert Rein, is contributing some of his services for free, Blum said.

The lawsuit contends that UT has run afoul of a 2003 ruling by the U.S. Supreme Court in a case involving the University of Michigan that said race and ethnicity could be considered under certain circumstances. Fisher's suit argues that affirmative action is allowed only after race-neutral approaches are found inadequate.

Patti Ohlendorf, UT's vice president for legal affairs, said the school's admissions policies comply with Supreme Court precedent and applicable laws.

"Each year, we are very fortunate to receive applications from thousands of very able high school seniors. But as with many universities around the country, we are limited in the number of applicants we can admit," she said.

This isn't the first time UT's admissions policies have been challenged in court. A 1996 federal court ruling involving UT effectively banned affirmative action at public colleges and universities in Texas. That prompted state lawmakers to enact the top 10 percent law in 1997.

After the Supreme Court's Michigan ruling, UT resumed considering race and ethnicity in admissions. UT officials contend that the top 10 percent law hasn't done enough to boost minority enrollment and have asked lawmakers to scale it back, saying that would allow them to enroll more minority students.

Fisher's lawsuit asks the court to end UT's consideration of race and to order that she be admitted if she qualifies under race-neutral factors. Blum, a 1973 graduate of UT and a part-time Austin resident, said hundreds of other students have been unfairly rejected, and he urged them to join the case.