To me, 'Check-a-box-and-vote' means a voter can check one box on their ballot to vote a straight party-line, or all candidates from one party.   How does that apply to illegal voters?  'Motor-voter' laws refer to the practice of voter-registration when a person applies for a driver's license.  Application for a (first) driver's license requires proof of age, which means a birth certificate.  A second or third license, say in a new state or country, you turn in your old license before they issue a new one.  That person must present proof of identity when voting.  What difference does it make whether it is a sanctuary state?