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New scholarship by Prof. Jonathan Klick links cell phone use to a decline in crime

December 17, 2012

New research by University of Pennsylvania Law School Professor Jonathan Klick, along with colleagues at Penn and George Mason University, links mobile phone use to a historic drop in the crime rate and urges policymakers to encourage individuals to carry their cell phones with them as a way to further deter crime.

The research paper “Mobile Phones and Crime Deterrence: An Underappreciated Link,” by Klick and co-authors John MacDonald, chair of Penn’s Department of Criminology, and Thomas Stratmann of George Mason University, has been issued by the Institute for Law and Economics, a joint research center of the Law School, the Wharton School and the Department of Economics.

The paper posits a novel contributing factor to help explain the remarkable crime decline of the 1990s, when crime rates dropped by about a third across all crime categories. The sharp reduction was unforeseen by social scientists and law enforcement officials, and finding explanations for it has been a central focus of modern empirical crime scholarship. That research has posited explanations of the decrease ranging from legalized abortion (culling the population of potential criminals), to increases in police forces, to changes in the market for crack cocaine, to rising incarceration rates (taking criminals off the streets).

Klick and his coauthors suggest a new partial explanation:  that the introduction and growth of mobile phone technology contributed to the crime decline, especially in the areas of rape and assault.

Noting that mobile phones enhance the ability of victims and witnesses to report crime to law enforcement authorities, the paper argues that such surveillance increases the risk of being apprehended when committing crimes against strangers. As a consequence, the authors propose, the expansion of cell phone use may have had a deterrent effect.

“Mobile phones allow for quicker reporting of crimes, and , in some cases, real time communication of details about the crime and the criminal,” the authors write. “The perceived risk of apprehension could increase among motivated offenders when they notice potential targets are carrying a mobile phone. As technology has improved to allow the transmission of photographic images, identification, apprehension, prosecution, and conviction all presumably become even more likely.”

The paper notes that the first commercially available mobile phone was introduced in 1983, but it wasn’t until the mid-1990s that the technology began to proliferate, a period that coincides with the beginning of the crime decline.

Further, other aspects of the crime decline – for instance, its concentration in urban areas and the fact that the decline was greatest in the Northeast – appear to match the geographic growth of the cell phone market, according to the researchers.

To test their hypothesis, the authors analyze state-level violent crime rates against the number of mobile phone subscriptions in a state in a given year. Although the empirical analysis doesn’t prove cause and effect, it demonstrates that more mobile phones in a state is strongly correlated with reduced violent crime measures.

“Our findings at least suggest some effect of mobile phones on sustaining the historically low rates of crimes of interpersonal violence between 1999 and 2007 in states,” the authors write.

While the widespread use of cell phones may already have realized the greater part of their crime deterrent effect, the authors conclude that law enforcement officials should promote their use. “By encouraging individuals to take cell phones with them when leaving their residences, cell phones have the potential to further reduce crime,” they write. They note that mobile phones, particularly those equipped with cameras, may have an especially important role to play in providing evidence in rape investigations.

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