 There's no exception carved out for people, for example, who may be registered at a homeless shelter or somewhere else that they can actually receive mail or where they actually are sleeping at night. She says this makes homeless voters uniquely vulnerable. Ultimately, a challenge could kick them off the rolls and not for a legitimate reason, voting rights advocates say. Andrew Garber is at the Brennan Center. He says it is important for voters to provide an address they can access.