Opponents of same-sex marriage didn’t find a sympathetic ear in a Chicago courtroom today as they urged federal appellate judges to reinstate bans on such unions in Indiana and Wisconsin.

“It’s based on hate, isn’t it?” Judge Richard A. Posner of the 7th U.S. Circuit Court of Appeals asked in response to one attorney’s contention that the prohibition on same-sex marriage is based on tradition.

Judge David F. Hamilton was skeptical of the contention that limiting marriage to opposite-sex couples promotes responsible procreation and encourages parents to stay together.

“I suppose you know how that’s been working out in practice,” he said, noting that births to single women rose 53 percent in Wisconsin and 68 percent in Indiana from 1990 to 2009.

Judge Ann Claire Williams rejected the notion that there is a good reason to prohibit same-sex couples from marrying.

“You can’t give us an answer — a harm, a legitimate government interest that is at stake,” she said to an attorney defending Wisconsin’s ban.

The judges fired their questions and comments at lawyers battling over separate rulings declaring Indiana and Wisconsin’s bans on same-sex marriage unconstitutional.

The arguments took place in the ceremonial courtroom of the Dirksen Federal Courthouse, which was packed with more than 200 spectators.

The panel did not immediately rule.

Same-sex marriage is legal in 19 states and the District of Columbia. In Illinois, the General Assembly lifted the ban on same-sex marriage in a statute that took effect this year.

In June, U.S. District Judge Barbara B. Crabb of the Western District of Wisconsin held that the state’s ban on same-sex marriage violated the due process and equal protection clauses. The same month, Chief U.S. District Judge Richard L. Young of the Southern District of Indiana made the same ruling about that state’s ban.

In an unrelated case, Young ruled last week that Indiana must recognize same-sex marriages solemnized in states where such unions are legal.

Crabb stayed her ruling on the same-sex marriage ban, and the 7th Circuit stayed Young’s while the appeals of Indiana and Wisconsin officials were pending.

In a brief filed with the 7th Circuit, attorneys for Wisconsin officials argued that the due process clause does not require the state to give same-sex couples the “positive right” to civil marriage.

Instead, the attorneys contended, Wisconsin may grant or withhold that right based on decisions made through the “democratic political process.”

In addition to protecting the democratic process, the attorneys argued, other rational bases for limiting marriage to opposite-sex couples include tradition, maintaining the status quo and recognizing the “procreative potential” of such couples.

In a separate brief, attorneys for Indiana officials also cited the possibility that opposite-sex couples can have biological children together as a reason to limit marriage to them.

Marriage, the attorneys wrote, “is a means of enticing individuals whose sexual intercourse may produce children to enter voluntarily into a relationship that the government recognizes and regulates for the sake of protecting and providing for any children the couple’s sexual union may produce.”

The attorneys also contended that the case for same-sex marriage “has no limiting principle.”

If same-sex marriages are entitled to constitutional protections, the attorneys wrote, then “all relationships are entitled to such recognition and regulation, whether they involve sex or not, whether they involve two people or more.”

Because same-sex couples cannot unintentionally produce a child, Indiana Solicitor General Thomas M. Fisher told the three-judge panel, “the state doesn’t need to nudge those couples to stay together.”

It’s a different matter when it comes to opposite-sex couples, he said.

“Men and women create babies, and there therefore has to be a social mechanism to deal with that,” Fisher said.

He rejected the notion that allowing opposite-sex but not same-sex couples to marry constitutes discrimination.

“This is about biology,” he said. “It’s simply that men and women make babies.”

Posner questioned why the government should be concerned only about “accidental births, unintended children” and not children who are adopted by their parents.

“Wouldn’t the children want their parents to be married?” he asked.

But Fisher contended that linking marriage rights with parental rights could cause problems if there are more than two people with parental rights over the same child.

“If marriage rights follow parental rights, then we’re looking at plural marriages,” he said.

During arguments in the Wisconsin case, Hamilton said it would be “problematic” if the court found there was a fundamental right to marriage but did not define marriage.

James D. Esseks of the American Civil Liberties Union in New York replied that there is no case law holding there can be no limits on a liberty right such as marriage.

Esseks, who represents plaintiffs who challenged the same-sex marriage ban in Wisconsin, argued that the benefits of marriage bestowed by the government should not be limited to opposite-sex couples.

And he said the status of being married “is enormously important to the plaintiffs.”

Camilla B. Taylor of the Lambda Legal Defense and Education Fund in Chicago argued that having married parents is important to the children of same-sex parents.

Taylor and Kenneth J. Falk of the American Civil Liberties Union of Indiana represent plaintiffs who challenged the same-sex marriage ban in that state.

Falk contended that “there’s absolutely no difference” between opposite- and same-sex marriages.

The people in those marriages, he said, all have the same constitutional right to marry.

The Indiana case is Marilyn Rae Baskin, et al. v. Penny Bogan, et al., Nos. 14-2386, 14-2387 and 14-2388.

Wisconsin Assistant Attorney General Timothy C. Samuelson argued on behalf of the state in the other case, Virginia Wolf, et al. v. Scott Walker, et al., No. 14-2526.