In a case that may turn on which is more important -- where a troubled family spends its days or its nights -- two groups plan to file suit today to keep four homeless students enrolled in Carlynton School District.

The Education Law Center and National Law Center on Homelessness and Poverty said they'll file suit in U.S. District Court in Pittsburgh, alleging Carlynton violated federal protections for the homeless by trying to deny the students admission to district schools.

The state Department of Education also will be named a defendant because it backs the district's efforts, the groups said.

The case could have national implications for enforcement of the McKinney-Vento Homeless Education Assistance Improvements Act of 2001, said Eric Tars, an attorney with the Washington, D.C.-based National Law Center.

School district Superintendent Michael A. Panza said family members use a "day shelter" in the Carlynton district but "aren't sleeping within the district."

The state has told the district it's "not responsible for the education of these children," Dr. Panza said.

A copy of the suit was provided by the Education Law Center, which has offices in Pittsburgh. The students -- 12- and 9-year-old girls and 6- and 5-year-old boys -- are identified by their initials.

After the father lost his job, the family was evicted from its home in Woodland Hills School District in April, the family's lawyers said.

The family accepted help from Interfaith Hospitality Network of the South Hills, which operates a shelter in Crafton, part of the Carlynton district.

The shelter functions as a "home" where the family has a room, keeps its possessions and receives various kinds of assistance. But overnight accommodations are provided on a rotating basis by eight churches, only one of which is in the district, the lawyers said.

The children finished last school year at Woodland Hills but sought enrollment at Carlynton in August. The district granted provisional enrollment after family members sought legal help, their lawyers said.

The children will continue to be enrolled at Carlynton pending the outcome of the dispute. Education Department spokesman Michael Race said that even if the family loses the case before the end of the school year, the children are welcome to remain at Carlynton for the rest of 2009-10.

Because of the alternating sleeping arrangements, the district and state claim the children aren't living in the district.

Mr. Race said the federal law determines homeless children's access to a school "by where they spend the night, not where they spend the day." He said the law's authors didn't foresee the possibility of multiple sleeping accommodations.

But the advocacy groups have a different take, saying McKinney-Vento allows homeless children to attend school where they are living and claim the family is living at the Crafton shelter.

If family members are turned away by other school districts in which they sometimes sleep, "they wouldn't have any school district, and that can't be right," law center attorney Nancy Hubley said.

Looking for more from the Post-Gazette? Join PG+, our members-only web site. You'll get exclusive sports content, opinion, financial information, discounts from retailers and restaurants, and more. Our introduction to PG+ gives you all the details.