Tighter background checks. Red-flag laws. An assault-weapons ban. Bans on high-capacity ammunition magazines. Democrats push the same set of policy prescriptions after each horrific mass shooting like Tuesday’s massacre of 19 children and two teachers at Robb Elementary School in Uvalde, Texas. Each time, Republicans claim that the problem isn’t guns, take umbrage at infringing upon Americans’ Second Amendment rights and stymie any move to even try to prevent future carnage. But as we suffer through yet another anguishing episode in our epidemic of gun violence, unique to the US, it’s time for a new idea — one based in...