Texas' foster care system is unconstitutional and should be reformed, according to a class action lawsuit that was filed against the state Tuesday.

The lawsuit, filed in federal court in Corpus Christi, claims Texas forces thousands of children to live in poorly supervised institutions and move frequently from one place to another. It also contends that children languish for years without permanent families, face a higher risk of abuse, are denied mental health services and are routinely separated from their brothers and sisters.

The suit was initiated by Children's Rights, a New York-based child advocacy group that regularly supports such legal action. The plaintiffs are nine children between the ages of nine and 16.

Marcia Lowry, the executive director of Children's Rights, said the 85-page pleading is the product of five years of scrutiny of Texas' child welfare practices by her organization. A ruling that the Texas system is unconstitutional would pave the way to reform, she said.

"This is a system that's been bad for a long time," Lowry said at a news conference in Dallas. "It's not going to turn around overnight, but it can be turned around."

According to Lowry, improving the system wouldn't necessarily require major new funding, even though the suit contends that the Texas Department of Family and Protective Services is "severely" understaffed.

"It's a question of where the state wants to put its money," she said. "There are ways to redesign the system."

Anne Heiligenstein, commissioner of the Department of Family and Protective Services, said Texas' foster children are safe, well-cared for and in a system that's nationally-recognized for seeking adoptive parents. The system has been subject to reform and has received more than $1 billion in additional funding in recent years, she said in a written statement.

"We're on the right path and will continue to do everything we can to protect Texas children, but I worry that a lawsuit like this will take critical time and resources away from the very children it presumes to help," Heiligenstein said.

According to statistics compiled by the agency, the number of caseworkers in Child Protective Services has risen in the last six years from 2,947 to 4,660. The number of adoptions consummated during that time period also has increased dramatically, from 2,512 to 4,803.

The Texas suit is the 12th class action initiated by Children's Rights seeking reform to the child welfare systems administered by state or municipal governments. Three other suits remain in litigation, and eight have been settled, according to the organization.

The suit names Gov. Rick Perry, Heiligenstein and Thomas Suehs, executive commissioner of the Texas Health and Human Services Commission, as defendants.