A judge in the Florida Keys overturned the state’s constitutional ban on same-sex marriage Thursday after a legal challenge by gay couples said it effectively made them second-class citizens.

The ruling by Circuit Judge Luis M. Garcia applies only to Monroe County, which primarily consists of the Keys, and will certainly be appealed. The lawsuit contended the same-sex marriage ban approved overwhelmingly by voters in 2008 violated the federal 14th Amendment’s guarantee of equal protection under the law. The judge said licenses could not be issued until Tuesday at the earliest.