MADISON, Wis. (AP) — In late December 2017, Lisa Kum received a call from her husband, Sothy.

Sothy told Lisa to pick him up in Chicago because he was about to be released after three months of detention by immigration authorities on a marijuana-related charge. On the drive from Wisconsin with their daughter Emma, she received another call: Sothy said there was a mistake, and Immigration and Customs Enforcement was not going to release him.

Instead, the agency deported him back to Cambodia. Sothy, who had lived in Wisconsin for most of his life, would not be able to come back to his home in Su...