NASHVILLE (AP) — Tennessee is turning away same-sex couples married in other states who seek to have their names changed on driver licenses and other state documents.State legislators banned same-sex marriage in a statute and voters did the same in the state constitution.The result is, as more Tennessee couples go to one of the 13 states and Washington, D.C., where same-sex marriages are recognized, they are having trouble getting it recognized back home. Complicating matters is the federal government now recognizes same-sex couples and allows Social Security cards to be issued in married names.The Tennessean reports attorneys are recruiting potential couples for a lawsuit challenging the state’s ban.University of Memphis law professor Steven Mulroy, who specializes in civil liberties, said there are two potential legal arguments against the ban — that it violates the U.S. Constitution’s equal protection clause because state laws can't discriminate — and that it violates the constitution’s full faith and credit clause, which says states must respect the judgment of other states.It’s impossible to count how many gay couples marry elsewhere and make their homes in Tennessee, but a University of California, Los Angeles study of 2010 census data puts the figure near 2,000. The number could be significantly higher with more states granting same-sex marriages.The issue with driver licenses is just one more reminder that same-sex couples’ marriages are unequal in Tennessee, said Chris Sanders, executive director of the Tennessee Equality Project.“The system we have is untenable because couples are changing all kinds of other federal documents and being given inconsistent guidance in Tennessee,” Sanders said.