Low graduation rates in Palm Beach County show the school district has failed its students, especially minority children, by not providing a "uniform, efficient, safe, secure and high-quality education," according to a lawsuit filed Tuesday by the American Civil Liberties Union.

The lawsuit addresses a topic never before challenged in the courts. The ACLU and other organizations have sued school districts for not distributing resources equally, but no group has pursued legal action for dismal graduation rates.

"We're really making a more basic point," said Chris Hansen, a senior staff attorney with the ACLU. "Graduating from high school is virtually the minimum requirement for success. A large percentage of the students are being essentially written off."

The suit alleges that the district is violating students' rights to a high-quality education as outlined in the state constitution.

According to state calculations, 71.8 percent of students across the county graduated on time last school year, up from 66 percent in 2003 but slightly below the state average.

The rate is higher than five of the other six largest "urban" school districts in the state, including Miami-Dade and Broward counties. Only Hillsborough County, at 79.1 percent, had a higher rate.

But the graduation rates drop off among the county's black and Hispanic students. While more than 80 percent of white students graduated on time in the county last year, only about 55 percent of black students and 64 percent of Hispanic kids did, according to state statistics.

The percentages may actually be slightly higher. School district officials initially submitted incorrect student information to the state, but the error has since been corrected. The district's total graduation rate increased from 71.4 percent to 71.8 percent in the correction, but the rates among particular races were not available Tuesday.

The three high schools with the highest percentage of black students - Palm Beach Lakes, Glades Central and Boynton Beach - also had the three lowest graduation rates in the county last year.

ACLU officials question the methods used to determine rates, including the addition of students who are pursuing a GED instead of a traditional diploma.

Different formulas cited in the suit, including one created by University of South Florida Professor Sherman Dorn that corrects for the GED students, put the county's graduation rate in recent years at less than 60 percent.

The suit calls for the school district to improve the graduation rates among students in every racial group, students who qualify for the school lunch program and English-language learners. It also calls for the school district to adopt a more-accurate method for calculating graduation rates.

It was filed on behalf of about a dozen Palm Beach County students and their parents and is meant to aid students of all backgrounds, said Muslima Lewis, director of the ACLU of Florida's Racial Justice Project.

"It is really about all graduation rates," Lewis said. "At the end of the day what we want is a graduation rate that increases for all students, and we want to monitor it to make sure that no particular group is left behind."

Hansen said the organization intentionally left out specific remedies to allow school district officials to do what they think is best to improve achievement.

"I would hope the county would look at this as a positive instead of a negative," he said. "What a lawsuit can do is help focus attention and resources."

Palm Beach County School District Superintendent Art Johnson would not comment on the lawsuit but said he is "absolutely not" content with the graduation rate as long as there are students failing.

"You have many students who have very challenging beginnings and the impact of society on them outside of school is enormous," Johnson said. "But, clearly, that can't be an excuse. We don't make any excuses. We know that's part of our job and we accept it."

School district officials had known of an impending suit since the ACLU began holding community meetings more than a year ago to find plaintiffs.

The school board voted last month to hire outside attorneys to assist the district in preparing for the suit.

At the time, school board Chairman Bill Graham called the possible suit "totally misdirected" and "misguided," arguing that most policies that hurt graduation rates come from Tallahassee lawmakers, not the school board. He could not be reached for comment Tuesday.

District officials received the lawsuit and are "reviewing it in detail," district spokesman Nat Harrington said.

"While we would like to respond with more, our policy is not to comment on pending litigation."