By Tim Ghianni

NASHVILLE, Tennessee (Reuters) - Tennessee must recognize the legal same-sex marriages of three couples who wed in other states, a federal judge in Nashville ruled on Friday in a limited decision that echoed a similar case in neighboring Kentucky.

Judge Aleta Trauger granted the couples a preliminary injunction that requires Tennessee to recognize their marriages pending a final decision on the constitutionality of Tennessee's ban on same-sex nuptials.

"At this point, all signs indicate that, in the eyes of the United States Constitution, the plaintiffs' marriages will be placed on an equal footing with those of heterosexual couples and that proscriptions against same-sex marriage will soon become a footnote in the annals of American history," Trauger wrote in the decision.

The ruling comes as gay rights advocates gain momentum in their fight to legalize same-sex marriage. Federal judges have recently struck down gay marriage bans in states including Utah and Texas. Such rulings have been put on hold pending appeals.

"This is the first nail in the coffin of marriage discrimination in Tennessee, and we won't stop until we have full marriage equality here. It will happen," said Abby Rubenfeld, the lead attorney in the case.

The trend follows a U.S. Supreme Court ruling in June that legally married same-sex couples nationwide are eligible for federal benefits. The decision struck down a key part of the 1996 federal Defense of Marriage Act.

Representatives for Republican Governor Bill Haslam and Attorney General Robert Cooper could not be reached immediately for comment.

Family Action Council of Tennessee President David Fowler said he expects Cooper will pursue an appeal if Trauger ultimately strikes down the state's marriage law.

Trauger "clearly signaled her intent to continue the war by unelected federal judges against the rights of states and the citizens of that to determine what its policies regarding marriage should be," Fowler said in a statement.

The couples in Friday's ruling, who were married in New York and California before moving to Tennessee, did not challenge the constitutionality of Tennessee's ban on same-sex marriage.

In February, a federal judge ordered Kentucky to recognize the legal same-sex marriages of residents who wed outside the state. Kentucky's governor plans to hire outside counsel to handle an appeal of that decision.

Same-sex couples can wed in 17 states plus the District of Columbia.

(Additional reporting by David Bailey in Minneapolis and Brendan O'Brien in Milwaukee; Editing by Cynthia Johnston, Lisa Shumaker and Richard Chang)

[Image: "Two Gay Men After Wedding On A Beach" via Shutterstock]