If the judges affirm Shelby's ruling, it will be the first federal appeals court to back the notion that same-sex couples have a fundamental right to marriage denied by laws like Utah's voter-approved Amendment 3. This will set a precedent for the approximately 60 cases pending in state and federal courts in 29 states and Puerto Rico.
Nine federal judges, including Shelby, have issued decisions in favor of the right of same-sex couples' access to civil marriage, which are now awaiting hearings before five appellate courts.
Reverse and remand •
The judges may choose to send the case back to the U.S. District Court in Salt Lake City with instructions perhaps asking for a trial on the merits of the social science claims made by both sides about children raised by gay and lesbian couples and other issues cited by the state as its rational for the ban.
These instructions or critiques of Shelby's ruling would be outlined in briefs prepared by the judges. Typically when a case is remanded, it is done so because the appellate judges disagree with the district judge's reasoning.
If a federal appeals court disagrees with the lower court's entire decision, it can "vacate" the case, which means it would render Shelby's ruling null and void.
This would restore Utah's asserted "status quo" in affirming Amendment 3's legality and declaring same-sex marriages illegal.
On to the Supreme Court •
Regardless of which way the court rules, it's likely the losing side will appeal the 10th Circuit Court's decision to the U.S. Supreme Court. The high court may opt to let the issue simmer, thereby leaving in place whatever determinations the circuit courts makes.
Supreme Court justices can pick and choose which cases they want to hear. So, they could opt to take on Utah's, and by extension the 10th District, or they could choose a more representative case like the 6th Circuit Court of Appeals, which, pundits have said, seems likely given that every state in its jurisdiction has gay marriage cases pending.