John Lott’s latest study refutes claims by anti-gunners that the presence of firearms on school campuses increases the chances of gun violence. President of his Crime Prevention Research Center, Lott’s study answered two questions raised by former Mayor Michael Bloomberg, the Giffords Law Center and others: 1) Does letting teachers carry a firearm on campus and in the classroom increase the chances of gun violence?; and 2) Does the presence of those teachers carrying legally deter mass shooters?