Vouching in Minnesota and How the Process Works.

Vouching: A registered voter from the same precinct can accompany a person to the polling place and sign an oath under penalty of perjury to confirm that person's address. (that's it, nothing more)

Registration: Once vouched for, the person completes a voter registration application and is added to the rolls.

Ballot Issuance: Because the voter is considered successfully registered at that moment, they are issued a regular ballot that is counted immediately with all other ballots.

In other words, there is no verification of legal status and the vote is cast. Your only option to keep someone from voting is to "Challenge" the voter's status and then they are given a provisional ballet that is counted at a later time.