"Both cases were ripe for review," Duncan said. "Now the Supreme Court has the opportunity to right the wrongs of lower court decisions."
Duncan's group filed amicus briefs in support of Prop 8.
The California law passed with 52 percent of the vote and was overturned in 2010 by a federal judge, and the 9th U.S. Circuit Court of Appeals affirmed that decision earlier this year. The Salt Lake City-based LDS Church spent $189,004 on the "Yes on 8" campaign, while businesses and individuals from Utah contributed $3.8 million to the campaign, more than 70 percent of it in support of Prop 8.
When the federal judge overturned the gay marriage ban, the LDS Church issued a statement saying it "regrets" the judge's decision.
"California voters have twice been given the opportunity to vote on the definition of marriage in their state, and both times have determined that marriage should be recognized as only between a man and a woman. We agree," the statement read. "Marriage between a man and woman is the bedrock of society."
But Brandie Balken, executive director of Equality Utah, said she hoped the U.S. Supreme Court would strike down the Defense of Marriage Act and that California's law would be deemed unconstitutional.
She also said she was happy to see the high court take on both cases though she was surprised the California one was added to the docket.
"I think we're hearing this conversation across the country and it is clearly a timely topic, and it will be very interesting to see how it plays out in the court," she said. "I'm hopeful it will give our community as a whole the opportunity to be treated as fully participating and fully valued citizens under the law."
In Utah, the state's constitution bans same-sex marriage and civil unions.
Clifford Rosky, associate law professor at the University of Utah and a member of Equality Utah's board, said he was also surprised the Supreme Court took up both cases and noted Justice Anthony Kennedy will be the one to watch. He said Kennedy has written two leading opinions on the issue of gay rights.
Rosky also said there is a wide possibility of outcomes that may not necessarily lead to a clear-cut resolution of rights. He said the court could simply look at the DOMA case and determine the legal counsel hired by Congress given the Obama administration's decision it wouldn't defend the act anymore doesn't have legal standing in the case.
He said that could lead to "chaos."
Rosky also said the ruling on one case could impact the other if it goes in favor of those supporting same-sex marriage.
"If the Supreme Court held that Proposition 8 were unconstitutional," he said, "it would be almost certain to say DOMA was unconstitutional as well."