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By David Mendoza - Tuesday, December 23, 2014

In 2006, Radley Balko published “Overkill: The Rise of Paramilitary Police Raids in America,” a prescient white paper given the current debate over police militarization. In it, Balko discussed the increasing use of police raids in America since the 1980s, describing scores of cases of police wrongly targeting people who were either innocent or nonviolent offenders. Balko’s work confirmed that these transgressions are not aberrations, but the consequence of the overuse of police raids and inadequate oversight. As Balko concluded, “The truth is, mistaken raids continue to happen with disturbing regularity. They can’t all be isolated incidents.”

Since the publication of “Overkill,” the Cato Institute has continued to collect examples of botched police raids and map the results. Cato’s map, shown below, certainly displays significant information, but its purpose is not immediately apparent. Cluttered with so many colorful pins, the map fails to show any compelling trend. Matthew Ericson, Deputy Graphics Director at The New York Times, faults results like this on the axiom “since the data CAN be mapped, the best way to present the data MUST be a map.” Instead, Ericson urges designers to avoid mapping data like this because it doesn’t show an interesting geographic pattern.

Map by the Cato Institute.

As shown at the top of the page, the data can be revisualized more effectively as a Sankey diagram. The redesign reveals several facts that the original map does not. First, it shows that there have been at least 379 botched raids since 1985 — or more than one a month for the last 29 years. Second, raids on innocent suspects represent the most common mistake. Third, California and New York tied for the most botched raids. However, this is probably because these states are, respectively, the largest and third largest states in the country.

I should acknowledge that the data is limited in many ways. Most importantly, as Balko noted, it is “by no means comprehensive.” For instance, the Cato Institute recorded no botched raids in 2012 and 2013, which is an unlikely occurrence. In a recent study by the ACLU, it examined more than 800 SWAT deployments between 2011 and 2012. They found that at least “36 percent of SWAT deployments for drug searches, and possibly in as many as 65 percent of such deployments, no contraband of any sort was found.” I also found a few errors in the data. Three examples of a raid on an innocent suspect — one in Florida, one in Georgia, and one in Iowa — were counted twice. One incidence in Alabama incorrectly identified the year a botched police raid was conducted in.

Note: “When Police Raids Go Wrong” is derived from “Botched Paramilitary Police Raids” by the Cato Institute, used under CC BY-NC-SA 3.0. “When Police Raids Go Wrong” is licensed under CC BY-NC-SA 4.0 by David Mendoza.