State child-welfare workers failed to honor their duties when they placed a knowingly abusive child in a home with other young foster children, an attorney for a Utah couple told a federal judge Monday.

For that reason, S. Brook Millard said, the workers should be held responsible for the young boy's physical and sexual abuse of the couple's soon-to-be adopted daughter.

"They put a foster child in harm's way," Millard said. "They breached their contract to protect that foster child."

The couple, identified in court documents only as J.W. and M.R.W., sued the Utah Department of Human Services and its former and current executive directors, the Division of Child and Family Services and its director, and several individual caseworkers last fall.

Attorneys for the state have filed a motion to dismiss most of the claims raised in the complaint on technical legal grounds. If the motion is granted, the only claims to remain would be the couple's breach-of-contract claim against DCFS and civil-rights claims against three caseworkers.

In a Monday hearing before U.S. District Judge Dale Kimball, Assistant Attorney General Barry Lawrence said the state agencies themselves, as well as state actors with no direct participation in the matter, are immune from the lawsuit.

"There has to be some sort of personal participation or active involvement, and that's certainly not alleged in the complaint," Lawrence said.

In their lawsuit, J.W. and M.R.W. allege state workers withheld information about the 6-year-old boy's history of "violent and sexually inappropriate conduct" and placed him in their home despite an agreement that the couple would not take foster children with such tendencies.

Kimball did not rule Monday on the state's motion to dismiss.