CHICAGO -- An appeals court declared that gay marriage bans in Wisconsin and Indiana violated the U.S. Constitution, on the same day that 31 states asked the Supreme Court to settle the issue once and for all.

The scathing, unanimous decision by a three-judge panel blasted the argument that only matrimony between a man and a woman should be allowed because it is -- simply -- tradition.

It also criticized another argument from the states that gays should not be allowed to marry because, on their own, they can't procreate, saying that rationale "is so full of holes that it cannot be taken seriously."

There are "bad traditions that are historical realities such as cannibalism, foot-binding, and suttee," says the ruling of the U.S. 7th Circuit Court of Appeals in Chicago. "Tradition per se therefore cannot be a lawful ground for discrimination -- regardless of the age of the tradition."

Wisconsin Attorney General J.B Van Hollen said he would appeal the ruling to the U.S. Supreme Court.

Also Thursday, Massachusetts and 14 other states where same-sex marriage is legal filed a brief asking the justices to overturn other states' bans on gay marriage.

Meanwhile, Colorado and 16 other states that have banned same-sex marriage filed a separate brief asking the court to rule one way or the other to clear up a "morass" of lawsuits.

Same-sex marriage is legal in 19 states and Washington, D.C. Bans that have been overturned in some other states continue to make their way through the courts. Since last year, the vast majority of federal rulings have declared same-sex marriage bans unconstitutional.

"Homosexuals are among the most stigmatized, misunderstood, and discriminated-against minorities in the history of the world," the 7th Circuit ruling says.

The opinion repeatedly mentions the issue of tradition, noting that some, such as shaking hands, may "seem silly" but "are at least harmless." That's not the case with gay-marriage bans, the court said.

A constitutional amendment approved in 2006 by voters banned gay marriage in Wisconsin, while state law prohibited it in Indiana.

The court's decision won't take effect for at least 21 days, said Camilla Taylor, a lawyer for Lambda Legal who argued on behalf of Wisconsin plaintiffs. That should give the states time to ask the Supreme Court to put it on hold, she said.Michael Tarm

The decision came unusually fast for the 7th Circuit -- just nine days after oral arguments -- suggesting unanimity came easily to the panel. The court's decisions typically take months. One of the three judges was appointed by Republican President Ronald Reagan, while the other two were appointed by Democratic Presidents Barack Obama and Bill Clinton.

One outstanding question is whether the U.S. Supreme Court will hear arguments on gay marriage.

Supreme Court justices typically take up issues only when lower courts disagree. But in this case, even victors in the lower courts may want the high court to address the question -- to settle the issue once and for all across the U.S.