Bloomberg wants to require background checks for all firearm sales and ban purchases by anyone younger than 21. Those rules would be effective in preventing murders like George Kemp’s only if young men like Corey Coleman are currently obtaining handguns from sources that can reasonably be expected to follow the new requirements, which is highly doubtful.

Bloomberg also wants to “make straw purchasing and trafficking stand-alone federal crimes, with serious penalties for offenders in order to help stop illicit sales.” Yet people who buy guns from federally licensed dealers already have to certify that they are not buying the guns for someone else, and lying about that is a felony punishable by up to 10 years in prison. The same penalty applies to anyone, including a private seller, who “knows or has reasonable cause to believe” that the person to whom he is transferring a gun is legally disqualified from owning it.