Interesting view of Parker v. DC
Over at Concurring Opinions, a former Ass't US Attorney for DC gives her take. She expects cert. to be granted, and adds "I think it's worth acknowledging the primary functions of the law as it's used by prosecutors in DC: the gun ban is both a preventive detention statute and an intelligence-gathering tool." That is, it wasn't employed for its own sake, but (1) it was used to lock up defendants whom they suspected, but could not prove, were violent, and (2) those allowed to plead out were required to agree to be debriefed about their knowledge of crime in the area.
Those seem rather doubtful objectives for a law of this type... but even so, could have been met with almost any other form of law, even permissive CCW licensing. Odds are that persons suspected of ongoing violence already have a criminal record that would disqualify them, or at the very least, wouldn't care for the attention that would follow filing an application.
Hat tip to Rob Allen.