The hearing before a three-judge panel of the 9th U.S. Circuit Court of Appeals also focused on whether supporters of voter-approved Proposition 8 have legal standing to challenge a lower court ruling that the ban was unconstitutional.
Attorney Charles Cooper, who represents sponsors of the ban, argued the state could treat same-sex couples differently when it comes to marriage without running afoul of the Constitution because "sexual relationships between men and women naturally produce children."
"Society has no particular interest in a platonic relationship between a man and a woman no matter how close it might be, or emotional relationships between other people as well, but when the relationship becomes a sexual one, society has a considerable interest in that," Cooper told the judges. "It's vital interests are actually threatened by the possibility of an unintentional and unwanted pregnancy."
Judge Stephen Reinhardt replied: "That sounds like a good argument for prohibiting divorce. But how does it relate to having two males and two females marry each other and raise children as they can in California and form a family unit where children have a happy, healthy home?"
The telecast attracted widespread attention for the issue after the court announced last month it had granted permission to televise live, federal proceedings on the case for the first time.
The January trial over Proposition 8 had been slated for broadcast on YouTube and at other federal courthouses. But the ban's backers objected, and the U.S. Supreme Court blocked the plan.
It's not unusual for the 9th Circuit to allow the televising of such hearings. It recently allowed a hearing on Arizona's controversial immigration law to be aired.
The issue of whether sponsors have legal standing in the case surfaced after outgoing California Gov. Arnold Schwarzenegger and Attorney General Jerry Brown both refused to challenge the ruling that overturned the ban. Schwarzenegger and Brown would have been responsible for enforcing the ban.
Cooper contended the coalition of religious and conservative groups that sponsored Proposition 8 should be allowed to appeal because of the moves by Brown and Schwarzenegger. However, his claim met skepticism by Judge N. Randy Smith.
"There is no question the attorney general has a duty to defend all the causes the state or any state official is a party in," Smith said. "Did you ever seek an injunction or an order or anything suggesting the attorney general should appeal and appeal?"
The panel of judges also grilled a lawyer representing Imperial County, which has sought to defend Proposition 8 if the appeals court determines the measure's backers do not have standing.
Judge Michael Hawkins repeatedly asked attorney Robert Tyler why his primary client was a deputy county clerk, not the elected clerk herself.
The panel appeared dubious about whether the ban's supporters were qualified to appeal but also seemed worried about allowing the governor and attorney general to effectively kill Proposition 8 by refusing to defend it.
"If the state does not defend it, it's just tossing in the towel," Judge Reinhardt said. "The governor is not allowed to veto this measure, but he can in effect veto it."
Plaintiffs attorney David Boies argued that the U.S. Supreme Court has repeatedly held that only parties with "a personal, concrete and particularized interest" in a case have authority to seek appeals court review.
Neither Imperial County nor the sponsors of Proposition 8 satisfy those conditions because marriage laws are a state function, Boies said.
Opponents of Proposition 8 contend it violates the due process and equal protection rights of gays and lesbians under the U.S. Constitution by denying them the right to marry the person of their choice and by singling them out for disparate treatment without a legitimate rationale.
Proposition 8's sponsors maintain that U.S. District Judge Vaughn Walker ignored U.S. Supreme Court precedents when he overturned the measure earlier this year.
Lawyers on both sides have said if they lose in front of the 9th Circuit they will take the case to the Supreme Court.
The televised hearing attracted large audiences at community centers catering to gays across the country. Law schools nationwide piped the proceedings into classrooms and auditoriums on campus.
The broadcast also rekindled debate over allowing cameras in the courtroom. The U.S. Supreme Court steadfastly refuses to allow televised broadcasts of its proceedings. A majority of the high court fear lawyers will grandstand in front of cameras, eroding the quality of oral arguments.
Before he retired and died, Chief Justice William Rehnquist also said he was concerned with the editing process. He feared that justices caught yawning or scratching their noses while sitting on the bench could be portrayed unfairly, taking away some of the court's dignity.
Yet, the U.S. Supreme Court's positions is increasingly becoming the exception rather than the rule. The 9th Circuit, for instance, occasionally allows broadcasts of its hearings.
Many state courts also allow televised broadcasts of hearings.
The California Supreme Court televises many of its oral arguments on a specialized government channel and allows mainstream television stations to broadcast cases with public interests.
Associated Press writer Paul Elias contributed to this report.