There is no real evidence that stop-and-frisk helps reduce crime

Imagine your doctor tells you that you have a serious wasting condition. Your physician prescribes a powerful kind of therapy that has serious side effects similar to chemotherapy’s. You ask what evidence there is of the therapy’s benefits. Your physician cheerfully says there’s none. She is prescribing the therapy because it has long been used — not because there’s real evidence that it does any good. This, in essence, is what commentators in Chicago, Philadelphia and elsewhere have recently proposed for the perennial challenge of gun violence: Return to an aggressive program of police stop-a...