In today's New York Times, op-ed columnist John Tierney plugs Reason contributor Radley Balko's upcoming Cato paper on the increasing use of highly aggressive, paramilitary tactics by U.S. police departments:

It's hard to know how many botched and unnecessary raids there have been, because police don't systematically track their errors, and the victims often have little recourse. But in a forthcoming report for the Cato Institute, Radley Balko concludes that mistakes have been made in more than 200 raids over the past decade.

He finds that overzealous raiders caused the deaths of a dozen nonviolent offenders, like recreational marijuana smokers and gamblers. In a Virginia suburb of Washington earlier this year, an optometrist being investigated for betting on sports was standing unarmed outside his town house, offering no resistance, when a SWAT officer's rifle discharged and killed him.

Balko also finds that two dozen people died in raids who were not guilty of any crime, like a Mexican immigrant killed by Denver police raiding the wrong home. Some died because they understandably assumed the masked invaders were criminals and picked up weapons to defend themselves. Some were innocent bystanders, like an 11-year-old boy shot in Modesto, Calif., and a 57-year-old woman in Harlem who had a heart attack when police set off a flash grenade during a raid based on a faulty tip.

Balko's research is the basis of a forthcoming Reason article–which, unlike Tierney's column, will be available online even to nonsubscribers (after a suitable lag to give our paying customers some value for their money, so if you want to read it as soon as possible you really should subscribe).