A federal commission rejected three states’ requests to ask voters for proof of citizenship, issuing a complex decision Friday that said it’s up to the national government, not the states, to decide what to include on registration forms. Under the motor-voter law, federal officials distribute voter-registration forms in all of the states. Arizona, Kansas and Georgia all asked that those forms request proof of citizenship, but the federal Election Assistance Commission rejected that in a 46-page ruling. The EAC said states can check driver’s license databases or ask federal immigration authorities for information, but they cannot tell the federal government...