Opponents of gay marriage in Illinois argue that Illinois gay and lesbian couples can access federal marriage benefits, provided they marry in a state which has legalized such unions.

The argument is part of a brief filed by the Thomas More Society, which intervened to defend the state's marriage laws after state officials refused to do so.

Cook County Judge Sophia Hall on Tuesday heard oral arguments in the lawsuit which involves 25 gay and lesbian couples who filed for marriage licenses but were denied.

In a motion filed last month, Lambda Legal and the Illinois chapter of the American Civil Liberties Union (ACLU) asked Hall for summary judgment in the case. Lawyers cited a Supreme Court ruling that struck down the Defense of Marriage Act (DOMA), which led to the federal government's recognition of the legal marriages of gay couples.

“Plaintiffs who obtained civil unions by license from Illinois county clerks, and those Plaintiffs whom Illinois deems as in civil unions because they entered into marriages in other jurisdictions that permit same-sex couples to marry, currently are uncertain of receiving, if not unlikely to receive, a number of federal benefits and protections that would be available to them and their families absent Illinois's marriage ban now that the federal Defense of Marriage Act (DOMA) has been struck down,” lawyers for the plaintiffs argued in a brief filed last month.

In its filing, the Thomas More Society argued that the DOMA case “says nothing about whether States must allow and/or recognize same-sex marriages” and suggested that gay couples could simply marry elsewhere to obtain federal benefits.

“Nothing in Windsor suggests that the availability of the federal benefits of marriage would be lost if a same-sex couple validly married in one State moved (or returned) to a State that does not allow or recognize such marriages. Thus, those plaintiffs who were lawfully married in another State (or who would marry in another State) may be eligible for all the federal benefits of marriage, regardless of the fact that Illinois does not allow or recognize such marriages (other than as civil unions).”