Twenty-five gay couples in Illinois who filed a lawsuit against the Defense of Marriage Act (DOMA), which outlaws a string of federal benefits for same-sex partners, were told today that the state would no longer defend it.

Although the Obama administration no longer defends DOMA at a federal level, individual states have continued to defend the 16-year old legislation — which was brought forth hurriedly when Hawaii seemed on the cusp of legalising equal marriage — as they are legally bound to.

Now, judges in several states, such as New York and Massachusetts, have moved to declare DOMA unconstitutional, and the law seems certain to be heading to the US Supreme Court.

Today, the attorney general of Illinois, Lisa Madigan, and Cook County’s state attorney, Anita Alvarez, both announced that they will no longer defend the anti-equality act, saying it violated the state constitution’s equal protection clause.

Legal experts in the state have expressed surprise at the announcement, as it is one step away from enabling judges to striking down the law itself. Meanwhile, sources familiar with the matter say that those who support the anti-gay legislation are grouping together to find someone who might defend it at court, though that in itself looks like a tall order

Speaking to the Associated Press, Ms Alvarez said: “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,” adding: “I’m not going to defend something I believe is in violation of the constitution.”

Ms Madigan, who has refused to speak publicly on the matter, seems set to file arguments next week in support of the plaintiffs, which the latter and gay rights activists have greeted with cheer.