Eight states where same-sex couples can marry are among 15 states urging the Supreme Court to uphold gay marriage bans and leave the matter to voters and lawmakers.
Louisiana and 14 other states are telling the justices in a brief filed Thursday that the court would do "incalculable damage to our civic life" if it decides that same-sex couples must be allowed to marry everywhere in the United States.
The states say they should be free to decide the issue for themselves.
Those seeking a nationwide decree in favor of same-sex marriage "urge the court to declare that the Constitution compels all 50 states to adopt this new form of marriage that did not exist in a single state 12 years ago. The court should decline that invitation," the states wrote.
Plaintiffs from Kentucky, Michigan, Ohio and Tennessee are asking the court to declare that the Constitution forbids states from denying same-sex couples the right to marry. The justices are scheduled to hear arguments on April 28.
Same-sex couples can marry in 37 states as a result of court decree, voter approval or legislative action.
The eight states on Thursday's legal filing where gay and lesbian couples can marry after courts struck down bans on gay marriage are: Alaska, Arizona, Idaho, Kansas, Montana, Oklahoma, Utah and West Virginia.
Seven other states where same-sex marriage remains illegal also joined the brief. They are: Arkansas, Georgia, Louisiana, Nebraska, North Dakota, South Dakota and Texas.
