Legal experts say the suit is a long shot, the St. Petersburg Times reported Monday.
Paula Schoenwether and Nancy Wilson, together for 27 years, were married July 2 in Massachusetts. Last week they filed a federal suit in Tampa asking U.S. District Court to force the state of Florida and the federal government to recognize their marriage legally.
Andrew Koppelman, a professor of law and political science at Northwestern University in Chicago said he favors same-sex marriage, but the suit "does not have a leg to stand on.
"I am a defender of same-sex marriage. I have every reason to want this couple to win. But this particular case sounds like a sure loser," he said.
The suit challenges the federal Defense of Marriage Act of 1996 and a similar law enacted in 1997 by the Florida Legislature. Both define marriage as a union between a man and a woman.