On the face of it, Friday’s decision by the Seventh Circuit Court of Appeals to overturn an injunction against enforcement of Illinois’ recently enacted ban on “assault weapons” and “large capacity” magazines doesn’t change circumstances on the ground. The three-judge panel that issued today’s decision had previously stayed U.S. District Judge Stephen McGlynn’s injunction while the state appealed, so the law has been in effect throughout litigation. Still, the 2-1 decision does matter, both because it provides an opportunity for some or all of the plaintiffs to appeal on an emergency basis to the Supreme Court and because it will...