A summary of the existing research evidence with links to more detailed information - part of our overview of "What works in policing to reduce crime".
Crime came down in New York City during the 1990s by more than in other US cities and, unlike those other cities, rates of imprisonment did not increase. The reasons for the decline aren't certain but police activity is thought to have played a part.
The New York police chief at the time has said that zero-tolerance (blanket enforcement of all laws without targeting) does not describe what happened, and that community policing and an organisational focus on crime reduction and quality of life issues were key. Regular performance meetings, called Compstat, were also believed to have helped encourage problem-solving as well as a focus on crime hotspots.
Read more: Evidence on zero-tolerance policing
Read more: Compstat