By Prosecuting Shooter’s Parent, Georgia Advances Legal Strategy

As the US grapples with a patchwork of firearms restrictions across states, prosecutors responding to mass shootings are looking more and more to hold parents culpable when their children take lives.

The latest example is Georgia, where a school shooter’s father faces charges—including second-degree murder, manslaughter and cruelty to children—after his 14-year-old killed four people. The Thursday charging announcement of Colin Gray answered how prosecutors would respond after the Wednesday shooting by a minor at Georgia’s Apalachee High School. Police say Gray “knowingly allowed” his son to use his semi-automatic rifle.

The charges echo those brought against the parents of ...