A California lawsuit yesterday challenged for the first time the relative lack of demanding high school courses available to students in predominantly minority, low-income schools.

The class action suit, filed in Los Angeles Superior Court by the American Civil Liberties Union of Southern California and Los Angeles attorney Johnnie Cochran, said California officials were violating the state constitution by generally providing fewer Advanced Placement (AP) courses in high schools with a high percentage of minority and low-income students than in schools with more white, affluent students.

The suit charges that this disparity causes many minorities to arrive at college ill-prepared for difficult math and science majors. It also argues that those same students may have more difficulty being admitted to University of California campuses because they have less opportunity to earn the extra grade point that comes with each successfully completed AP course.

Access to AP courses has become an important topic in national discussions over how to close the nagging gaps between the academic achievements of whites and nonwhites. In May, the U.S. Department of Education's office of educational research and improvement reported that the quality of a student's high school curriculum is a better predictor of college success than test scores, grades or class rank.

"California is flunking out when it comes to educating these students," said Mark Rosenbaum, legal director of the ACLU of Southern California. He said the state is "denying them intellectually challenging courses designed to prepare them for college, and holding them back by squelching their competitive chances of acceptance at colleges and universities."

State Superintendent of Public Instruction Delaine Eastin said through a spokesman that she agrees more teachers in the state must be trained to teach AP courses and that she has tried to broaden the availability of such training. But the law, she noted, still gives each local district the power to decide how many AP courses its schools will offer.

In fact, California does better than most states in providing AP courses, which teach subjects at an introductory college level and give students a chance to earn college credit in high school. About 85 percent of California high schools -- compared with just 51 percent of all U.S. high schools -- offer at least one AP course.

Yesterday's lawsuit was filed on behalf of four students at Inglewood High School in Los Angeles County, where more than 97 percent of the student body is African American or Hispanic. According to the suit, the school offers only three AP courses, none of them in science or mathematics. (An administrator at the school declined to comment on the case.)

By contrast, the suit notes that Beverly Hills High School -- a Los Angeles County school where only 8.8 percent of the students are African American or Hispanic -- offers 14 AP courses, including chemistry, physics, biology, computer science and two different calculus courses.

As an example of the difference a challenging curriculum can make in an inner-city school, the lawsuit cites Garfield High School in East Los Angeles. Due to the efforts of teachers such as Jaime Escalante and Ben Jimenez, the overwhelmingly Hispanic, low-income school offered a dozen AP courses in the late 1980s, and had more students taking AP calculus than all but four other high schools in the country in 1987. Though those numbers have dropped since Escalante left in 1991, they remain well above average.