In his opinion in Kitchen v. Herbert, federal district judge Robert Shelby held

that Utah’s prohibition on same- sex marriage conflicts with the United States Constitution’s [Fourteenth Amendment] guarantees of equal protection and due process under the law. The State’s current laws deny its gay and lesbian citizens their fundamental right to marry and, in so doing, demean the dignity of these same-sex couples for no rational reason. Accordingly, the court finds that these laws are unconstitutional.

Notably, Utah has both a state statute and state constitutional amendment defining marriage as limited to "a man and a woman."

The judge interestingly relied upon Justice Scalia's dissenting opinion in last term's decision in United States v. Windsor, which held §3 of DOMA unconstitutional:

The Constitution’s protection of the individual rights of gay and lesbian citizens is equally dispositive whether this protection requires a court to respect a state law, as in Windsor, or strike down a state law, as the Plaintiffs ask the court to do here. In his dissenting opinion, the Honorable Antonin Scalia recognized that this result was the logical outcome of the Court’s ruling in Windsor: In my opinion, however, the view that this Court will take of state prohibition of same-sex marriage is indicated beyond mistaking by today’s opinion. As I have said, the real rationale of today’s opinion . . . is that DOMA is motivated by “bare . . . desire to harm” couples in same-sex marriages. How easy it is, indeed how inevitable, to reach the same conclusion with regard to state laws denying same- sex couples marital status. 133 S. Ct. at 2709 (citations and internal quotation marks omitted). The court agrees with Justice Scalia’s interpretation of Windsor and finds that the important federalism concerns at issue here are nevertheless insufficient to save a state-law prohibition that denies the Plaintiffs their rights to due process and equal protection under the law.

Perhaps most controversially, Judge Shelby determines that marriage is a fundamental right and that restrictions on marriage merit strict scrutiny. He further finds that there is no compelling governmental interest justifying the same-sex marriage restriction, unlike, for example, a regulation of the age at which a person may be married which is supported by the compelling state interest of "protecting children against abuse and coercion."

Judge Shelby's opinion on equal protection grounds is much less controversial, and perhaps even conservative. Judge Shelby rejects the arguments - - - or at least the need for the arguments - - - regarding any sort of heightened scrutiny and resolves the case on rational basis review. This rejection includes the arguments centering on animus as a non-legitimate state interest. Instead, he concludes that the legitimate government interests that Utah cites are not rationally related to Utah’s prohibition of same-sex marriage. These interests include the by now familiar ones of "responsible procreation," "optimal child-rearing," "proceeding with caution," and "preserving the traditional definition of marriage."

He ends with an extended analogy to Loving v. Virginia, or more specifically, Virginia's arguments in the landmark case ruling the state's anti-miscengation law unconstitutional. And after clearing declaring sections 30-1-2 and 30-1-4.1 of the Utah Code and Article I, § 29 of the Utah Constitution unconstitutional under the Fourteenth Amendment, enjoins their enforcement.