Katie Couric’s gun control documentary “Under the Gun” was released May 15 without any portion of a four-hour interview conducted with John Lott, Jr. Lott is president of the Crime Prevention Research Center and a known gun scholar whose seminal work is More Guns, Less Crime. On May 6, Lott tweeted that he had been “interviewed for 4 hours” for Couric’s film and he “bet” that four hours would be reduced to a “select few minutes” of actual screen time. The reduction happened alright. But instead of using those select few minutes, Couric and director Stephanie Soechtig cut Lott’s interview...