In an important but narrow ruling, a U.S. district court judge in Nashville issued a preliminary injunction late Friday afternoon, barring the state of Tennessee from denying recognition of marriage licenses obtained by three same-sex couples in other states.

The order applies only to these three couples and only while their lawsuit challenging the state’s refusal to recognize marriage licenses obtained by same-sex couples else is pending, said Shannon Minter, legal director for the National Center for Lesbian Rights. But it represents yet another important victory for marriage equality, and another advance in a southern state.

NCLR and long-time lesbian legal activist Abby Rubenfeld filed the lawsuit, Tanco v. Tennessee, on behalf of four couples last October. (One couple subsequently dropped out of the lawsuit.) It challenges both the state constitutional language and statutory laws that ban recognition of the marriages of same-sex couples. Like so many other lawsuits filed in more than two dozen states around the country, the Tennessee lawsuit argues that the bans violate the couples’ rights to due process and equal protection under the U.S. Constitution.

Judge Aleta Trauger (a Clinton appointee) said in the order she issued Friday that “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 also noted that other pending lawsuits in other states may well determine the ultimate outcome of the Tanco challenge.

NCLR’s Minter pointed out that the lawsuit which just concluded a two-week trial in Detroit, for instance, could be appealed to the Sixth Circuit U.S. Court of Appeals relatively soon and potentially deciding the law for other Sixth Circuit states, such as Tennessee.

The lead plaintiffs, Drs. Valeria Tanco and Sophy Jesty are both professors of veterinary medicine who married in 2011, while living in New York. Other plaintiffs include Sergeant First Class Ijpe DeKoe and Thomas Kostura married while living in New York, and John Espejo and Matthew Mansell, who married in California.

Judge Trauger’s order noted that each couple, “When they interact with Tennessee officials or fill out official forms to identify themselves as married, they brace themselves for degrading experiences that often occur because of Tennessee’s refusal to recognize their marriages.”

The Tennessean newspaper reported Friday evening that the state’s attorney general is expected to defend the state’s ban; no word yet on whether the state will attempt to challenge Trauger’s very limited order.