Last night, a crowd of lawyers, activists and officials filled NYU’s Greenberg Lounge for a heated debate on the causes of the city’s unprecedented drop in crime and prison population.

The debate centered around a data-driven report, published earlier this month by Vera Institute of Justice and the Brennan Center for Justice. The report was featured in a recent New York Times article with the reporter coming to the conclusion that there was one primary reason: more policing.

But many people at last night’s debate felt that the New York Times either misinterpreted the report or that the report over-emphasizes the role of policing, while ignoring a whole host of other possible reasons why crime fell: unemployment and poverty rates, immigration, people moving upstate, a change in drug markets… and the trouble might be in trying to simplify and quantify the reasons at all.

Since the mid-1990s, the city has been policed based on the “broken windows” theory of increasing arrests for misdemeanors and quality of life infractions. Broken windows turned into “Hot spot” policing and “stop and frisk,” both controversial techniques that target high-crime neighborhoods and impact people of color disproportionately.

The only thing everyone seemed to agree on was that the number of people in prison has gone down because less people were arrested for felonies. Donna Lieberman, Executive Director of the NYCLU, underlined the obviousness of this statement with a simple “Duh.”

The report’s authors, Michael Jacobson from Vera and criminologist, James Austin, were disappointed that a passionate debate over “stop and frisk” (efficacy vs social costs) derailed what was intended to be a discussion of reducing mass incarceration.

From CompStat to broken windows and even to former NYPD Commissioner, Bill Bratton, New York City is known for exporting it’s criminal justice innovations, so last night’s debate goes far beyond the walls of NYU’s law school. Both Vera and the Brennan Center are influential in criminal justice policy-making, and many other towns and cities will be looking to New York City to tackle their own problems with over incarceration.