A U.S. appeals court panel that barred Kansas, Alabama and Georgia from adding a proof-of-citizenship requirement to a federal voter registration form wrote Monday that federal law leaves it to a federal elections agency — not the states — to determine whether such a change is ­necessary. The 2-to-1 written opinion follows a Sept. 9 order from the U.S. Court of Appeals for the D.C. ­Circuit. The panel wrote that although the document requirement “unquestionably” hinders voter registration groups ahead of the November elections, there was “precious little” evidence of voter fraud by noncitizens, the problem the states said the measure is intended to fight. The Kansas secretary of state had told the court that “between 2003 and 2015 eighteen noncitizens had tried to or successfully registered to vote. Only one of them attempted to use the Federal Form,” the judges wrote.