In a federalist system with more than 15,000 state and local law enforcement agencies and virtually no standardized reporting requirements, reliable and comprehensive data on police behavior, including the presence and usage of militarized units, have eluded scholars for decades. And even those with the time and resources to gather and assemble the records themselves face systemic barriers.
I sent hundreds of open records requests to local agencies in search of data on militarization, but learned that many agencies purge records that are more than five or 10 years old, or don’t track the activity of their militarized units at all. When they do, they often track it poorly, refuse to share it, or release heavily redacted records that are of little use citing exceptions to open records laws which, quite unhelpfully, vary by state. In other cases, agencies demand exorbitant fees, (sometimes tens of thousands of dollars), as payment for the person-hours they claim it would take to compile police records.
More readily available data on police agencies often require substantial preprocessing to be useable. A federal government survey intended to reach all police agencies in the country every four years, for example, included a question about whether agencies provide Special Weapons and Tactics (SWAT) services in their jurisdictions in 2000, 2004 and 2008. But the data contain no consistent agency IDs, making comparisons between these surveys a painstaking task.
In the wake of Ferguson, the federal government released data from its 1033 Program, an initiative that has sent billions of dollars in surplus military equipment to thousands of local agencies since the 1990s. For empirical social scientists like me, the data set appeared at first glance to be a treasure trove. But I found that records of older equipment shipments were incomplete, making the data ill-suited for estimating the causal effects of militarization, as opposed to merely identifying its correlates.
I eventually located usable data from Maryland, which passed a law in 2009 that required every police agency in the state to record SWAT activity in a uniform manner. The data represent the most complete and fine-grained portrait of SWAT activity I know of, and include the date and zip code of more than 8,000 deployments, as well as a host of outcomes including whether police fired shots, damaged property, or made arrests.
These data were not generated to satisfy some benevolent desire for transparency among Maryland officials. Rather, they were collected in response to intense political pressure following a botched SWAT raid in which a local sheriff’s department forced its way into a suburban Maryland mayor’s house, shot and killed his two dogs, and interrogated him and his wife on unfounded suspicion of drug trafficking. In response to public outrage, Maryland officials passed legislation mandating the uniform collection of SWAT data statewide, but only until the political storm blew over—the legislation included a sunset clause that ended the reporting requirement after five years.