Yesterday Sen. Dianne Feinstein (D-Calif.) revealed that her "assault weapon" ban will not be part of the gun control bill that Senate Democrats plan to offer next month. Although her bill still can be offered as an amendment, Politico reports, "its exclusion from the package makes what was already an uphill battle an almost certain defeat." At the risk of reading too much into this delightful development, I count it as a victory not just for the Second Amendment but for rationality in lawmaking. As a comparison of the testimony pro and con readily reveals, supporters of Feinstein's bill never...