The Cato Institute has published a paper by Agitator blogger Radley Balko on the increased use of paramilitary tactics by local polices forces, Overkill: The Rise of Paramiltary Police Raids in America. Here is the executive summary:

Americans have long maintained that a man's home is his castle and that he has the right to defend it from unlawful intruders. Unfortunately, that right may be disappearing. Over the last 25 years, America has seen a disturbing militarization of its civilian law enforcement, along with a dramatic and unsettling rise in the use of paramilitary police units (most commonly called Special Weapons and Tactics, or SWAT) for routine police work. The most common use of SWAT teams today is to serve narcotics warrants, usually with forced, unannounced entry into the home.

These increasingly frequent raids, 40,000 per year by one estimate, are needlessly subjecting nonviolent drug offenders, bystanders, and wrongly targeted civilians to the terror of having their homes invaded while they're sleeping, usually by teams of heavily armed paramilitary units dressed not as police officers but as soldiers. These raids bring unnecessary violence and provocation to nonviolent drug offenders, many of whom were guilty of only misdemeanors. The raids terrorize innocents when police mistakenly target the wrong residence. And they have resulted in dozens of needless deaths and injuries, not only of drug offenders, but also of police officers, children, bystanders, and innocent suspects.

This paper presents a history and overview of the issue of paramilitary drug raids, provides an extensive catalogue of abuses and mistaken raids, and offers recommendations for reform.

There is an interactive map of botched paramilitary operations accompanying the study here. See also Balko's post on the study here.

UPDATE: Balko addresses early feedback to his study here.