Six gay couples filed a lawsuit Tuesday seeking to overturn Florida’s ban on same-sex marriage, the latest in a series of cases across the country that contend such prohibitions are unconstitutional and effectively relegate gay partners to second-class status.

The lawsuit was filed in Miami-Dade Circuit Court on behalf of the couples by Equality Florida Institute Inc., a civil rights organization that works for fairness for gay, lesbian, bisexual and transgender people. The lawsuit claims Florida’s gay marriage ban violates the U.S. Constitution’s guarantees of equal protection and due process.