A Cook County, Illinois judge is expected to rule Friday on whether a lawsuit challenging the state's ban on gay marriage can proceed.

Circuit Judge Sophia Hall heard oral argument in the case on August 6.

The case involves 25 gay and lesbian couples who requested marriage licenses in Cook County, which includes Chicago, but were denied.

Illinois currently recognizes gay couples with civil unions. A marriage bill stalled in the House after passage in the Senate on Valentine's Day. Activists are lobbying for a final House vote during the upcoming fall session, but the bill's champion in the House, Rep. Greg Harris, has signaled that he's considering tabling the bill until next year.

(Related: Illinois gay marriage bill might not see House vote this year.)

Plaintiffs in the case are represented by Lambda Legal and the Illinois chapter of the American Civil Liberties Union (ACLU), whose lawyers asked Judge Hall for summary judgment in the case soon after the Supreme Court struck down the Defense of Marriage Act (DOMA).

(Related: Illinois gay marriage opponents argue gay couples should marry elsewhere.)

The socially conservative Thomas More Society intervened to defend the state's marriage laws after state officials refused to do so.