Do Police Matter? An Analysis of the Impact of New York City's Police Reforms

This study evaluates explanations that have been advanced for the sharp decline in crime in New York City during the 1990s. The authors consider arguments that crime drops have been the result of socio-economic factors, such as an improving economy, falling numbers of teenaged males, and declining use of crack cocaine. They also consider the argument that police interventions—particularly the enforcement of laws against minor crimes, known as "broken windows" policing—played a major role.

The study concludes that:

• "Broken windows" policing is significantly and consistently linked to declines in violent crime.
• Over 60,000 violent crimes were prevented from 1989 to 1998 because of "broken windows" policing.
• Changes in the number of young men of high-school age were not associated with a decline in violent crime.
• Decreasing use of crack cocaine was also not associated with a decline in violence.
• Other changes in police tactics and strategy may also be responsible for some of the City's drop in crime. Case studies conducted in six City police precincts in 2000 show that precinct commanders often use "Compstat" technology to identify when specific types of crime, such as robberies or burglaries, become unusually serious problems. Incidences of such crimes often fell after the commanders employed specifically devised tactics to combat the identified problem.
• As implemented by the NYPD, "broken windows" policing is not the rote and mindless "zero tolerance" approach that critics often contend it is. Case studies show that police vary their approach to quality-of-life crimes, from citation and arrest on one extreme to warnings and reminders on the other, depending upon the circumstances of the offense.

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