The Milwaukee Police Department has just released some new data on traffic and subject stops. There is a fascinating story here on policing strategy. Since 2007, Milwaukee has experiened a dramatic increase in the number of stops: both traffic and subject stops are up close to 250%. This has been part of a deliberate strategy to increase the number of police-citizen contacts, especially in high-crime neighborhoods. (The MPD has also been very active over the past four years in promoting uncoerced police-citizen contacts, too.) The objectives are to gather intelligence, disrupt criminal activity, and enhance community perceptions of safety in public spaces.

As hoped, crime has indeed gone down considerably since 2007: violent crime is down 24%, and property crime is down 21%. Whether and to what extent the increased-stops strategy has caused the crime drop is uncertain — the MPD has also made some other significant changes in the past four years, and, in any event, crime has been dropping nationwide — but the causal claim strikes me as at least facially plausible. Providing some additional support is a month-by-month breakdown of auto theft and robbery data: in general, in months when stops have lagged, auto thefts and robberies have gone up; in months when stops have increased, auto thefts and robberies have dropped.

But safety has a cost.