In an interview with The New York Times, Attorney General Eric Holder stated that state attorneys general are not obligated to defend unconstitutional laws.

“Mr. Holder was careful not to encourage his state counterparts to disavow their own laws, but said that officials who have carefully studied bans on gay marriage could refuse to defend them,” the Times reported on Monday.

Six Democratic state attorneys general have already taken that step, refusing to defend such laws before judges in cases challenging them.

“Engaging in that process and making that determination is something that's appropriate for an attorney general to do,” Holder said.

“If I were attorney general in Kansas in 1953, I would not have defended a Kansas statute that put in place separate-but-equal facilities,” Holder said, a reference to Brown v. Board of Education, the landmark Supreme Court ruling which found unconstitutional state laws establishing separate public schools for black and white students.

Attorneys general in Nevada, Pennsylvania, Virginia, California, Illinois and most recently Oregon have refused to defend laws that prohibit gay couples from marrying.

Wisconsin Attorney General J.B. Van Hollen, a Republican who is defending his state's ban, told the Times that it wasn't Holder's job “to give us advice on defending our constitutions any more that it's our role to give him advice on how to do his job.”

“We are the ultimate defenders of our state constitutions,” he added.

(Related: Eric Holder: Justice to treat marriages of gay couples equally.)