CHICAGO — Federal appeals judges bristled on Tuesday at arguments defending gay marriage bans in Indiana and Wisconsin, with one Republican appointee comparing them to now-defunct laws that once outlawed weddings between blacks and whites.

As the legal skirmish in the United States over same-sex marriage shifted to the three-judge panel of the 7th U.S. Circuit Court of Appeals in Chicago, more than 200 people lined up hours before to ensure they got a seat at the much-anticipated hearing.

While judges often play devil’s advocate during oral arguments, the panel’s often-blistering questions for the defenders of the same-sex marriage bans could be a signal the laws may be in trouble – at least at this step in the legal process.

Richard Posner, who was appointed by President Ronald Reagan in 1981, hit the backers of the ban the hardest. He balked when Wisconsin Assistant Attorney General Timothy Samuelson repeatedly pointed to “tradition” as the underlying justification for barring gay marriage.

“It was tradition to not allow blacks and whites to marry – a tradition that got swept away,” the 75-year-old judge said. Prohibition of same sex marriage, Posner said, derives from “a tradition of hate … and savage discrimination” of homosexuals.

Attorneys general in both states asked the appellate court to permanently restore the bans, which were ruled unconstitutional in June. Its ruling could affect hundreds of couples who married after lower courts tossed the bans and before those rulings were stayed pending the Chicago appeal.

Gay marriage is legal in 19 states as well as the District of Columbia, and advocates have won more than 20 court victories around the country since the U.S. Supreme Court ordered the federal government to recognize state-sanctioned gay marriages last year.

Posner, who has a reputation for making lawyers before him squirm, cut off Indiana Solicitor General Thomas Fisher, just moments into his presentation and frequently chided him to answer his questions.

At one point, Posner ran through a list of psychological strains the children of unmarried same-sex couples suffered, including having to struggle to grasp why their schoolmates’ parents were married and theirs weren’t.

“What horrible stuff,” Posner said. What benefit to society in barring gay marriage, he asked, outweighs that kind of harm to children?

“All this is a reflection of biology,” Fisher answered. “Men and women make babies, same-sex couples do not… we have to have a mechanism to regulate that, and marriage is that mechanism.”

While the judges seemed to push defenders of the bans the hardest, they also pressed the side arguing for gay marriage to say just where they themselves would draw the line about who could and couldn’t marry.

Would they argue in favor of polygamy on similar grounds, by pointing to the emotional toll on children in families with multiple mothers or fathers, asked Judge David Hamilton, a President Barack Obama appointee.

“If you have two people, it’s going to look like a marriage,” said Kenneth Falk of the American Civil Liberties Union of Indiana. “If you have three or four, it doesn’t. … There’s no slippery slope.”

A voter-approved constitutional amendment bans gay marriage in Wisconsin. State law prohibits it in Indiana. Neither state recognizes same-sex marriages performed elsewhere. The lawsuits that led to Tuesday’s hearing in Chicago contend that the bans violate the U.S. Constitution’s equal protection guarantee.

Despite the seriousness of the hearing, there was some levity.