CHICAGO — Illinois Attorney General Lisa Madigan and Cook County State’s Attorney Anita Alvarez on Thursday announced that they will not defend Illinois’s 16-year-old ban on same-sex marriage.

Both attorneys said that the ban, which defines marriage as between a man and a woman, violates the Illinois state constitution’s equal protection clause.

“I took an oath when I was sworn in to defend the constitution of the state of Illinois and I believe that’s what I’m doing,” Alvarez said in an interview with the Chicago Tribune.

“I’m not going to defend something I believe is in violation of the constitution,” she said.

Lawsuits representing 25 Illinois couples who had applied for marriage licenses have been filed by the American Civil Liberties Union and New York-based Lambda Legal challenging the state’s ban on same-sex marriage.

The suits name Cook County Clerk David Orr as a defendant; Orr’s office is responsible for issuing marriage licenses in the county, which includes the city of Chicago. Some of the couples were from outside the county and the city but had applied to his office and were denied.

Camilla Taylor, marriage project director for Lambda Legal said Thursday’s announcements by Madigan and Alvarez reflect “a tipping point” because “our government finds these laws indefensible.”

“It comes at a time when a form of discrimination against a class of people in our society is so shameful and reprehensible that it’s incapable of defense,” said Taylor.

The decision by the prosecutors to not defend the law has raised eyebrows among the legal community in the state who believe prosecutors are legally bound to defend Illinois law.

Experts also maintain that this situation could lead to a judge knocking down the statute in a single ruling.

Supporters of the same-sex marriage ban say it’s “unconscionable” that there will not be a legal advocate arguing for the “people” in court to defend it, and some are contemplating how to intervene.

The state’s Democratic Governor Pat Quinn recently announced his support for same-sex marriage, however legislative efforts to legalize it remain stalled in the General Assembly.

Also on Thursday, a Cook County judge granted the suing parties’ request to combine the two lawsuits.