He twice cited the Supreme Court's ruling this summer that the federal Defense of Marriage Act was motivated by animus, or the "bare...desire to harm" homosexuals. He agreed with Justince Antonin Scalia's dissent that it was impossible not "to reach the same conclusion with regard to state laws denying same-sex couples marital status."

But unlike Scalia, Shelby said the right to homosexual "marriage" is not a new right but "is deeply rooted in the nation's history and implicit in the concept of ordered liberty."

He called Loving v. Virginia, the 1967 U.S. Supreme Court case that struck down state laws against interracial marriage, an "analogous case" of discrimination. The suit, filed by the ACLU filed in 1964, received a unanimous decision from the Warren Court.

If upheld, Shelby's decision could overturn the constitutional amendments in 28 other states that forbid same-sex "marriage."

"This is federal, so if this judge is right, all 50 states must legalize same-sex 'marriage,'" said Clifford Rosky, a homosexual activist and law professor at the University of Utah. "The logic of this decision is not limited to Utah in any way."

Pro-family activists have also warned of the potential scope of the decision, as well as its top-down imposition on the conservative state.

"This ruling is a travesty of justice," Brian Brown, president of the National Organization for Marriage, said. "This ruling should concern every American who cares about the rights of citizens and their involvement in determining the laws that govern us."

In 2004, 66 percent of state voters approved Amendment 3 to preserve the definition of marriage.

State officials seemed taken aback by Judge Shelby's decision. Shelby deliberated just 16 days before writing his opinion, after hinting that he may not rule until early January.

Utah Governor Gary Herbert said he was "very disappointed an activist federal judge is attempting to override the will of the people of Utah."

He promptly filed an appeal with Denver's Tenth Circuit Court not to issue marriage licenses until a final decision is made, arguing the idea that "same-sex marriage is a fundamental right has never been established in any previous case in the 10th Circuit."

But the Tenth Circuit Court denied a temporary stay on Sunday and turned down a second appeal this morning. During a 9 a.m. hearing this morning, Shelby likewise refused an emergency motion to hold up the issuance of licenses pending further appeals.

If Shelby's ruling is overturned, any marriage licenses issued to same-sex couples at this time would be invalidated - something that happened previously when a rogue county clerk in Pennsylvania flouted state law by issuing marriage licenses to gay couples.

County clerks in Utah are pondering how to deal with the ruling. While Salt Lake officials rushed to recognize gay "marriages," the clerk in Provo, the county seat of Utah County, has refused to give homosexuals a marriage license. "Until I receive the further clarification that I'm seeking" from the state and county attorneys general, "the Utah County Clerk's Office will not be making any policy changes in regards to which we issue marriage licenses," said Utah County Clerk Bryan E. Thompson.

Shelby's ruling came one day after the New Mexico Supreme Court legalized gay "marriage" by overturning existing state practice and stating that county clerks must issue marriage licenses to same-sex couples. Both states have large Mormon populations.

NBC News, the parent company of MSNBC, noted, "The ruling, which made Utah the 18th state to allow same-sex nuptials, marked a major victory for gay rights activists in a conservative state where the Mormon Church wields considerable influence."

Mormons played a leading role in the campaign to pass Proposition 8, the state constitutional amendment protecting marriage passed by California voters in 2008. This summer, the Supreme Court let stand a lower court ruling striking it down as unconstitutional.

If Shelby's ruling is upheld, Utah would become the 18th state to legalize same-sex "marriage"; nine of those were imposed by judicial rulings rather than a popular vote. In only three states - Maine, Washington, and Maryland - has same-sex "marriage" been ratified by voters in a popular referendum.

"This trend of vetoing the voters from the bench must be stopped," Brown said. "It's becoming increasingly clear that the people of America need to reclaim their sovereignty and amend the US Constitution to protect marriage as the union of one man and one woman."