Richard Wolf

USA TODAY

WASHINGTON — The march toward making same-sex marriage legal nationwide takes a giant step forward this week in one of the most conservative parts of the country.

Appeals of federal district court rulings that sanctioned gay marriages in Utah and Oklahoma will be heard by a three-judge panel of the 10th Circuit Court of Appeals in Denver on successive Thursdays, moving the issue closer to a return engagement at the Supreme Court.

Since the high court issued two landmark rulings last June granting federal recognition to same-sex marriages and clearing the way for gay and lesbian weddings in California, every lower-court decision has struck down bans on gay marriage.

Now it's time for appeals courts to weigh in — first in the Utah and Oklahoma cases, followed by Virginia next month. Cases also are pending from Kentucky, Michigan, Nevada, Ohio, Tennessee and Texas.

"This just takes it one step closer to the Supreme Court, which will likely decide the matter for the entire country," says Roberta Kaplan, the lawyer for Edith Windsor, whose victory in last year's case striking down part of the federal Defense of Marriage Act has led to the current winning streak.

After years spent waging political and legislative battles, proponents of gay marriage have turned almost exclusively to the courts since last year. Keeping track of the lawsuits requires a scorecard: The Human Rights Campaign counts 57 cases in 27 states, while Freedom to Marry, another advocacy group, counts 61 cases in 30 states. All told, the cases have nearly 550 plaintiffs.

Trying to figure out which will be the case eventually granted by the Supreme Court has become a parlor game in legal circles. The Utah and Oklahoma cases are on the fastest track, but that's no guarantee either of them will be chosen. The Virginia case features the same lawyers who represented California's same-sex couples last year, but the state attorney general's refusal to defend the same-sex marriage ban could make it less attractive to the justices.

And while the ultimate goal of gay rights groups is winning marriage rights in all 50 states, some of the cases raise a lesser issue: Should states without same-sex marriage be forced to recognize married couples from other states? The high court might choose to address that question first.

"I think there will be a menu of cases for the court to consider" in its next term beginning in October, says Mary Bonauto of Gay & Lesbian Advocates & Defenders, a pioneering gay rights attorney whose lawsuit led to Massachusetts becoming the first state in the nation to legalize same-sex marriage in 2004.

THE 10TH CIRCUIT CASES

The Utah and Oklahoma cases challenge state constitutional amendments passed in 2004, in the wake of the Massachusetts decision.

Three same-sex couples challenged the Utah ban last year, including one couple seeking to have its Iowa marriage recognized. U.S. District Judge Robert Shelby ruled in December that the ban denied Utah residents a "fundamental right," demeaning "the dignity of these same-sex couples for no rational reason."

More than 1,000 couples were married in Utah before the Supreme Court halted the process pending appeals. That has left those couples in a marital no-man's-land — their marriages neither voided nor fully recognized by the state. About 300 Michigan couples are in the same boat following a similar process last month. In all other states, district judges stayed their own rulings.

"It's untenable to think about stripping away a couple's marital status," says Shannon Minter, a lawyer with the National Coalition for Lesbian Rights, who is representing the Utah plaintiffs. "It would be devastating for those families and their children."

The Oklahoma case was filed nearly a decade ago, but it wasn't until January that U.S. District Judge Terence Kern ruled that the state's ban "discriminates ... without a legally sufficient justification." By then, the Supreme Court had said that denying federal benefits to legally married couples was violated the Constitution.

"Supreme Court law now prohibits states from passing laws that are born of animosity against homosexuals, extends constitutional protection to the moral and sexual choices of homosexuals, and prohibits the federal government from treating opposite-sex marriages and same-sex marriages differently," Kern said. "This court knows a rhetorical shift when it sees one."

Still, Austin Nimocks of Alliance Defending Freedom, a lawyer in the Oklahoma and Virginia cases, says the states retain the right to enact their own marriage laws. Same-sex marriage, he notes, is not rooted in American history or tradition.

"Even on appeal, the burden remains on the plaintiffs to demonstrate that there is no rational basis for this law," Nimocks says.

Both cases will be heard by the same three-judge panel, which includes judges nominated by the last three presidents — George H.W. Bush, Bill Clinton and George W. Bush.

FROM VIRGINIA TO NEVADA

Other appeals will be heard later this year, beginning with Virginia in May and likely including cases from Michigan to Texas to Nevada. The 6th Circuit is made up of four states — Michigan, Ohio, Kentucky and Tennessee — all of which have same-sex marriage appeals teed up.

The last decision upholding a state's ban came in the 9th Circuit, where a district judge OK'd Nevada's prohibition in November 2012.

"Since then, the landscape has changed dramatically," says Susan Sommer of Lambda Legal Defense and Education Fund, who is representing eight same-sex couples in that case. The legal winning streak that has followed the Supreme Court decisions represents "the wind in our sails" as the case moves to the appellate level, she says.

Only five states — Alaska, Georgia, Montana, North Dakota and South Dakota — ban same-sex marriage without so much as a court challenge. That may change soon; a lesbian couple from South Dakota plans to wed in Minnesota this spring and seek to have the marriage recognized back home.

"Every district court decision, especially from states that are considered to be more conservative, helps," says James Esseks, a lawyer with the American Civil Liberties Union, which is involved in 10 cases nationwide.

Appeals courts, as the last stop before the Supreme Court, often take more time than busy trial judges to consider cases and come to surprising conclusions, says John Eastman, chairman of the National Organization for Marriage and a professor at Chapman University School of Law in California. He's optimistic at least some appeals courts will uphold gay marriage bans.

"The reason the appellate courts are there is to sort out the very difficult legal issues and dwell on them longer," Eastman says. "I suspect we may well have different decisions from the courts of appeals."

The string of court decisions has helped to spur other forms of momentum. The Human Rights Campaign, the nation's largest gay rights organization, is beefing up its staff. Freedom to Marry just began a television advertising campaign featuring Republican former senator Alan Simpson of Wyoming. National and state polls regularly show support for same-sex marriage above 50%.

"We have to create the climate for the courts to do the right thing," says Evan Wolfson, founder and president of Freedom to Marry. "We have to be making the same strong case in the court of public opinion as our advocates make in the court of law."