COLUMBIA, S.C. (AP) - South Carolina Attorney General Alan Wilson is formally appealing a judge's ruling that tossed out the state's ban on same-sex marriages.

Wilson on Thursday filed a notice he would be appealing to the 4th U.S. Circuit Court of Appeals in Richmond, Virginia. He has called the ruling no surprise and that he is obligated to defend state laws.

In the case of a Charleston couple suing to be married, U.S. District Judge Richard Gergel ruled Wednesday South Carolina's constitutional ban is "invalid as a matter of law."

The appellate court has already found a similar ban against same-sex marriages in Virginia unconstitutional.

South Carolina is now the only state in the circuit not allowing same-sex marriages. But Wilson says South Carolina's marriage laws aren't identical to those in other states.