There is, of course, a civil-liberties cost to enlarging the police net. Similarly, although the police have caught major drug traffickers by searching the vehicles of motorists stopped for traffic offenses on the New Jersey Turnpike, their success is counterbalanced by unsuccessful but intrusive vehicle searches of otherwise respectable citizens who made an illegal turn or drove faster than the speed limit. And a disproportionate number of those stopped were black or Hispanic. True, most blacks and Hispanics are law-abiding. It is an unfortunate fact that much higher proportions of black children than white grow up at a social disadvantage and are more tempted to break society's rules.
Some police officers are no doubt racists and some are guilty of misconduct.
But it is dangerous to make public policy on the basis of such horrible examples as the Amadou Diallo shooting. Fairness requires that mistakes be looked at in the context of the more numerous examples of good judgment. But the police deserve extra leeway for their mistakes because, unlike other professionals, they don't have the luxury of turning down unpleasant cases. They make house calls despite personal danger. They have to deal with not only criminals but also paranoid schizophrenics who have not taken their medication or suicidal people.