(Chicago Tribune) — The American Civil Liberties Union of Illinois got the go-ahead Monday to intervene in a lawsuit and join the state’s battle against Catholic Charities’ policy of turning away prospective parents who are in civil unions.

Catholic Charities in Joliet, Peoria, Springfield and Belleville filed the lawsuit this summer, asking a Sangamon County judge to uphold their policy of providing publicly funded foster care and adoption services only to married couples and single parents living alone, while referring couples in civil unions to other agencies.

On Monday, the judge allowed the ACLU of Illinois to intervene after lawyers argued that allowing Catholic Charities to reject parents based on sexual orientation or religious belief violates the federal consent decree designed to improve conditions for children in the care of the Illinois Department of Children and Family Services.

ACLU lawyers said the consent decree requires the state to consider nothing but the “best interests of the child,” not the religious beliefs of a private foster agency, when making decisions about placement.

“Catholic Charities is ruling out possible parents based on factors that have nothing to do with the best interests of the children,” said ACLU lawyer Karen Sheley.