On Thursday, the judges spent most of their time either questioning Campbell or debating whether the plaintiffs sued the correct person and had legal standing for the court to intervene. The case has taken 10 years to reach this point, partly because another 10th Circuit panel in 2009 ruled the plaintiffs incorrectly sued the governor and attorney general and directed them to name a different party. The plaintiffs then sued the county clerk who denied them a marriage license.
The panel allowed the hearing to run 13 minutes over its 30-minute limit so it could further question Campbell on his arguments.
Oklahoma voters overwhelmingly approved that state's gay marriage ban in 2004. A federal judge in January ruled that the ban violated the constitutional rights of gays, triggering the appeal. That is almost identical to the Utah case, in which a federal judge struck down that state's 2004 voter-approved gay marriage ban in December.
Legal experts say the Oklahoma and Utah cases are almost identical, though Utah does not have the same standing issues as Oklahoma. The justices' decision likely will pivot on the level of deference they believe a court should give voters to deny a group of people the ability to marry.
It might be months before a written ruling is issued. Similar appeals are working their way through four other appellate court circuits, and it is unclear which case would next reach the Supreme Court, which likely will have the final word on the issue.
Two of the plaintiffs in the Oklahoma case, Sharon Baldwin and Mary Bishop, told reporters outside the courthouse that they wanted to marry but have made a point of trying to change the law in their home state rather than travel to one of the 17 states that permits gay marriage.
"We believe that history and justice are on our side, and that is something that no amount of tradition can overcome," Baldwin said.
Campbell told reporters he also felt the hearing went well but declined to make a prediction based on the judges' questioning.
"I don't play the game of reading judges," Campbell said. "It's a dangerous game."
Associated Press writer Colleen Slevin contributed to this report.