The three-judge 10th Circuit panel ruled 2-1 that Oklahoma's law denied gay couples their "fundamental right," but stayed its decision as the state considers an appeal.
Utah has already appealed its decision to the Supreme Court, meaning the nation's highest bench will have a choice between the two decisions in taking up the constitutionality in all gay marriage bans.
"Oklahoma's ban on same-sex marriage sweeps too broadly in that it denies a fundamental right to all same-sex couples who seek to marry or to have their marriages recognized regardless of their child-rearing ambitions," wrote Judge Carlos Lucero in his decision. "As with opposite-sex couples, members of same-sex couples have a constitutional right to choose against procreation."
Like in the Utah case, Lucero was joined by Judge Jerome A. Holmes. Judge Paul Kelly Jr., dissented in both cases, arguing that Oklahoma voters should have the ability to define marriage in their state.
"Same-gender marriage is a public policy choice for the states, and should not be driven by a uniform, judge-made fundamental rights analysis," Kelly wrote.
In 20 court cases across the country since the Supreme Court issued a pair of landmark decisions in 2013, so far primarily in federal district courts and in state courts, same-sex marriage is on a winning streak lending the issue a sheen of inevitability.
An additional six states have legalized gay marriage by court order or legislative action, bringing the total of states with legal same-sex marriage to 19 states and the District of Columbia.
The next ruling is likely to come from Virginia, where a federal appeals court heard arguments in May.