Tribal police chief Michael Valenzuela drove through darkened desert streets, turned into a Circle K convenience store and pointed to the spot beyond the reservation line where his officers used to take the non-Indian men who battered Indian women.

“We would literally drive them to the end of the reservation and tell them to beat it,” Valenzuela said. “And hope they didn’t come back that night. They almost always did.”

About three weeks ago, at 2:45 a.m., the tribal police were called to the reservation home of an Indian woman who was allegedly being assaulted in front of her two children. They said her 36-year-old non- Indian husband, Eloy Figueroa Lopez, had pushed her down on the couch and was violently choking her with both hands.

This time, the Yaqui police were armed with a new law that allows Indian tribes, which have their own justice system, to prosecute non-Indians. Instead of driving Lopez to the Circle K and telling him to leave the reservation, they arrested him...