Breaking ranks with rulings from other federal courts, the 6th U.S. Circuit Court of Appeals panel in Ohio upheld gay marriage bans in four states, saying the courts aren't the right place to legalize gay marriage. Here's a look at key passages and how they compare to previous federal rulings:
1. ON CHILDREN
THE LATEST: The 6th Circuit ruling says that limiting unions to being only between a man and a woman is a view shared "not long ago by every society in the world, shared by most, if not all, of our ancestors, and shared still today by a significant number of the States."
People may not need the government's encouragement to have sex or "propagate the species," it says, but they may need encouragement to "create and maintain stable relationships within which children may flourish."
"Imagine a society without marriage. It does not take long to envision problems that might result from an absence of rules about how to handle the natural effects of male-female intercourse: children," the opinion says. "May men and women follow their procreative urges wherever they take them? Who is responsible for the children that result?"
The judges acknowledge that gay and lesbian couples are equally capable of being in loving, committed relationships and effectively raising children. But those facts don't mean states must suddenly believe gay marriage bans violate the constitution, the opinion says.
EARLIER RULINGS: The San Francisco-based 9th Circuit said the proposition that children suffer in same-sex households "reflects a crass and callous view of parental love and the parental bond that is not worthy of response. We reject it out of hand."
The Denver-based 10th Circuit scoffed at the attempts by Utah and other states to use procreation as a justification for gay marriage bans. In a majority opinion written by Judge Carlos Lucero, the court pointed out that adoptive parents and opposite-sex couples who rely on assistance to get pregnant aren't denied the right to marry. They said they don't buy the contention that same-sex couples are inferior parents.
2. ON POLYGAMY
THE LATEST: The 6th Circuit ruling suggests making gay marriage legal could open the door for others such as polygamists to claim their unions also constitute legal marriage.
"There is no reason to think that three or four adults, whether gay, bisexual, or straight, lack the capacity to share love, affection, and commitment, or for that matter lack the capacity to be capable (and more plentiful) parents to boot," it says. "If it is constitutionally irrational to stand by the man-woman definition of marriage, it must be constitutionally irrational to stand by the monogamous definition of marriage."
EARLIER RULINGS: The 10th Circuit rejected the "slippery slope" argument that contends legalizing gay marriage would lead to acceptance for polygamy. "Unlike polygamous or incestuous marriages, the Supreme Court has explicitly extended constitutional protection to intimate same-sex relationships," the ruling said.
3. ON STATES' RIGHTS
THE LATEST: States should be able retain authority to define marriage as between a man and woman to ensure the incentive to stay together for their children remains, the 6th Circuit opinion says.
"That does not convict the States of irrationality, only of awareness of the biological reality that couples of the same sex do not have children in the same way as couples of opposite sexes and that couples of the same sex do not run the risk of unintended offspring," it says.
EARLIER RULINGS: In its June ruling striking down Utah's gay marriage ban, the 10th Circuit dismissed as "wholly illogical" the notion that states allowing gays to wed could somehow undermine traditional marriage. Judge Carlos Lucero wrote for the majority. "We may not deny them relief based on a mere preference that their arguments be settled elsewhere."
4. ON THE SUPREME COURT
THE LATEST: The 6th Circuit makes note that the U.S. Supreme Court's decision on Oct. 6 to turn away appeals from five states seeking to prohibit gay and lesbian unions does not end the debate on the constitutionality of gay marriage bans.
"A decision not to decide is a decision not to decide," Circuit Judge Jeffrey Sutton wrote.
EARLIER RULINGS: Other appeals courts have agreed that the high court has not given clear guidance on the issue. About the Supreme Court's ruling in June 2013 that overturned part of a federal ban on gay marriage, the 10th Circuit wrote: "While Windsor is the only Supreme Court case concerning same-gender marriage, it simply did not decide the issue of state prohibitions on same-gender marriages."