A Harris County, Texas, grand jury refused Monday to indict Joe Horn, a 62-year-old retiree, in the shooting death of two men who were burglarizing his neighbor’s house.

The facts in the case are well-known. Back in November, Horn saw two men breaking into his neighbor’s house in Pasadena, Texas. He called 911. The operator told him several times to remain in his house until police arrived, but Horn declared he was not going to let them get away with the crime and that he was “going to kill them.”

And that’s just what he did. He got a shotgun, went outside and confronte...