BOSTON GLOBE: “Effectiveness of D.C. gun ban still a mystery.”

“One of the difficult things is, you can’t measure what didn’t happen,” Singer said. “You can’t measure how many guns didn’t come into the District because we have this law.”

But you can measure the violence that did occur, using the bellwether offense of homicide to chart the ebb and flow of crime in the District since the ban was enacted. And the violence here over those years was worse than in most other big cities, many of them in states with far less restrictive gun laws. . . . Yet the gun culture on the city’s mean streets during the crack epidemic has not abated, police statistics show. Even as the homicide toll declined in D.C. after 1991, the percentage of killings committed with firearms remained far higher than it was when the ban was passed.

“Mystery?” By any reasonable measure, it was a failure. And a predictable one, since gun control hasn’t done much for crime anywhere in the United States.