The filing leaves the two lawsuits virtually unchallenged by Illinois officials.

Alvarez is charged with defending Cook County Clerk David Orr in lawsuits brought by Lambda Legal and the American Civil Liberties Union (ACLU) that claim Orr's refusal to issue marriage licenses to same-sex couples is unconstitutional.

"We are in agreement with the plaintiffs that Illinois laws that prohibit same sex marriage are unconstitutional," said the state's attorney's office in a statement. "We believe the plaintiffs are correct in their assertion that the Illinois Constitution upholds marriage equality for same sex couples just as it does for opposite-sex couples."

Orr, a longtime LGBT ally, has repeatedly stated that he supports the lawsuits.

"Government should not be in the business of discriminating," Orr said at a June 14 press conference at the Daley Center.

Attorney General Lisa Madigan has also filed to intervene in support of the suits, stating that the ban on same-sex marriage is unconstitutional. As a result, no elected official who can counter the lawsuits will do so.

The two lawsuits, filed simultaneously in the Circuit Court of Cook County, represent 25 same-sex couples that tried to obtain marriage licenses from Orr's office but were denied. If successful, the suits would result in marriage equality throughout the state.

The lawsuits argue that civil unions, which began a year ago, have failed to provide same-sex couples with the same rights and symbolic meaning conferred by marriage. As a result, plaintiffs argue that the ban on same-sex marriage violates the state's equal protection clause.

"Civil unions brand these couples as worth less than other families, and children feel that," said Camilla Taylor, national marriage project director of Lambda Legal.

The lawsuits will not go unopposed, however.

Peter Breen—executive director of the Thomas More Society, a law firm that opposes same-sex marriage—said his firm will file to intervene against the lawsuits.

Breen alleged the suits were an attempt to "make an end run around the legislation" and speculated that the lawsuits were "an inside job" between LGBT organizations, Orr, Madigan and Alvarez.

Breen's firm is the same one that represented a group of Catholic charities that unsuccessfully sued the state over foster care contracts. The charities lost those contracts for refusing to place children with same-sex parents.

Breen said his firm will defend the ban because officials have failed to do so.

Reporters pressed Alvarez on the legality of refusing to fight the lawsuits, which she said had correctly interpreted the law.

Asked if the lawsuits put her in a difficult position politically, Alvarez responded that they did not.

"It's not an uncomfortable position for me to be in," she said. "It is a little unusual."

Alvarez has been vocal about LGBT rights in the past, including her support for marriage equality.

Ed Yohnka, director of communications for the ACLU of Illinois, said his organization was pleased but not surprised by the filings.

"It is not surprising that after the state's attorney and her colleagues were able to review our complaint and the Illinois Constitution, they reached the same conclusion," he said. "Most of all, we are happy that we are one day closer to winning the freedom to marry for our plaintiffs and for thousands of couples across Illinois."