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Criminology

When police forces grow, homicides drop and low-level arrests increase
A person wearing a "POLICE" vest and a walkie talkie, standing in front of a blurry police car with its lights flashing.

When police forces grow, homicides drop and low-level arrests increase

Research from Penn criminologist Aaron Chalfin and others found that an additional 10 to 17 officers prevented one homicide annually, but each extra officer added up to 22 arrests for crimes like drug possession.

Michele W. Berger

Almost 500 people dead: Philadelphia is about to set a grim record for homicides
Philadelphia Inquirer

Almost 500 people dead: Philadelphia is about to set a grim record for homicides

Aaron Chalfin of the School of Arts & Sciences spoke about the rise in gun violence that accompanied the pandemic. “So many things changed at the same time, and that means that it’s very hard to disentangle what the drivers are,” he said. “I don’t know that we ever fully will.”

Portland among US cities adding funds to police departments
Philadelphia Inquirer

Portland among US cities adding funds to police departments

Aaron Chalfin of the School of Arts & Sciences said crime rates can fluctuate based on police department budgets and officer numbers, as well as shifts in the economy, infrastructure, and community programming. There are “a million things that drive crime up and down,” he said.

‘Re-fund the police’? Why it might not reduce crime
The New York Times

‘Re-fund the police’? Why it might not reduce crime

Research by Aaron Chalfin of the School of Arts & Sciences found that 54% of the time, hiring more police officers accompanied a drop in homicides. However, increased hires are also linked to more arrests for low-level offenses and more costs to cities due to increased police violence, legal settlements, and protests.

America can’t fix policing without fixing the country’s gun problem
Vox.com

America can’t fix policing without fixing the country’s gun problem

Aaron Chalfin of the School of Arts & Sciences said the heavy reliance on police in the U.S. is the result of a failure to address the root causes of crime and violence. “The police are the residual claimants on all the stuff that no one else is willing or able to deal with,” he said. “We put them in that position.”

The role of progressive prosecutors in the criminal justice reform movement
A close up to the an ornamental scale in an office with law books on shelves behind it.

The role of progressive prosecutors in the criminal justice reform movement

Using Philadelphia as a microcosm, a new law course will analyze the emerging trend of progressive prosecutors’ offices and discuss how their strategies fit into a larger movement for criminal justice reform.

From Penn Carey Law

Murders are spiking. Police should be part of the solution
Vox.com

Murders are spiking. Police should be part of the solution

Aaron Chalfin of the School of Arts & Sciences spoke about the need for a nuanced evaluation of police work. “The idea that we can reduce the violence we’ve been seeing without any use of the police is not evidence-based; it’s an aspiration, and it’s a high-risk idea,” he said. “A balanced portfolio feels like the lowest-risk strategy to me.”

The story of immigration enforcement
paperwork for citizenship and immigration with U.S. flag

The story of immigration enforcement

In an award-winning paper, criminologist Aaron Chalfin examines the public safety implications of labor market-based immigration enforcement.

From Omnia

COVID-19, protests, and crime
Three police cars with sirens flashing are seen in a line from behind police crime tape at night

How did the COVID-19 pandemic and last summer’s racial justice protests affected America’s crime rate? Two undergrads worked with Law professor David Abrams to find out.

COVID-19, protests, and crime

During a summer internship with the Law School’s David Abrams, rising sophomores Caroline Li and David Feng looked at how the COVID-19 pandemic and last summer’s racial justice protests affected America’s crime rate. 

Kristen de Groot