If you click on his website, Rick Nevin looks like a movie star in the photo that appears and not the statistics aficionado that he is. Nevin’s site has much more than a glossy photo. It contains lots and lots of thoughtful statistical analysis and well-written reports about crime rates. Although he has no training as a criminologist, Nevin has a Masters in Finance, Managerial Economics, and Strategy from Northwestern University and a Masters in Economics and Bachelors in Economics and Mathematics from Boston University, according to his profile at Healthy Housing Solutions, Inc., where is on the staff.
Nevin has an idea that has captured the attention of many serious people including Professor Doug Berman at Sentencing Law and Policy (SL&P). Basically, that idea is this: If you crunch the data, lead exposure levels better account for variations in violent crime rates than any other single variable including especially stiffer sentences. Most recently, Doug posted about an additional analysis that Nevin sent to him. See SL&P, Finding an age-based silver lining — or lead lining — in latest BJS prison data (September 17, 2014). Rather than summarize what Doug wrote, I find it more accurate to quote him including the hyperlinks and “emphasis added” in his post. That is:
Regular readers know I am very intrigued by the (often overlooked) social science research that suggests lead exposure levels better account for variations in violent crime rates than any other single variable. Consequently, I am happy an eager to note this new data and analysis sent my way by researcher Rick Nevin who has been talking up the lead-exposure-violent-crime link for many years.
This short new piece by Nevin, titled “Prisoners in 2013: The News Media Buries the Lead,” responds to yesterday’s report from the Bureau of Justice Statistics that the US prison population increased in 2013 for first time since 2009. Without vouching for the data, I am eager to highlight Nevin’s interesting and encouraging age-based data discussion (with bolding in original and a recommendation to click through here to see charts and all the links):
The news media is reporting on U.S. incarceration data from the Bureau of Justice Statistics (BJS), but the media and BJS have ignored the important news: From 2012 to 2013, the male incarceration rate fell 21% for men ages 18-19, 6% for ages 20-24, and 5% for ages 25-29, but increased by 5% for ages 50-54, 7% for ages 55–59, and 8% for ages 60–64.
BJS Prisoner Series data show an ongoing incarceration rate decline for younger males and an increase for older males that has been ignored by the media for more than a decade. From 2002 to 2013, the male incarceration rate fell by 61% for men ages 18-19, 34% for ages 20-24, and 25% for ages 25-29, but increased by 30% for ages 40-44.
BJS data for older age groups, reported since 2007, show the same trend through the age of 64. From 2007 to 2013, the male incarceration rate fell 37% for ages 18-19, 28% for ages 20-24, 14% for ages 25-29, and 7% for ages 30-44, as the male incarceration rate increased 22% for ages 45-49, 50% for ages 50–54, and 57% for ages 55–64. In 2007, men ages 18-19 were twice as likely to be incarcerated as men ages 60-64. In 2013, men ages 60-64 were almost 20% more likely to be incarcerated than men ages 18-19.
The BJS Prisoners in 2013 report ignores the detailed data on trends in male incarceration rates by age, and highlights an increase in the total prison population of about 4,300 from 2012 to 2013, but notes that the overall incarceration rate (per 100,000 U.S. residents) did fall from 480 in 2012 to 478 in 2013….
The actual BJS data show a long-term trend of falling incarceration rates for younger men that has continued from 2002 through 2013. That decline was the inevitable result of a shift in violent crime arrest rates by age since the 1990s. From 1994 through 2011, the violent crime arrest rate fell by 64% for ages 13-14, 61% t0 52% for ages 15-18, 44% to 39% for ages 19-21, 37% for ages 22-39, and 19% for ages 40-44, as the violent crime arrest rate increased by 6% for ages 45-49, and 13% for ages 50-54.
What is the causal force behind the shift in age-specific violent crime arrest rates and incarceration rates? The Answer is Lead Poisoning.
For the sake of argument, I am about to assume that Nevin is right. But before I do, and without intending to be all-inclusive, I next list four caveats because I am skeptical that Nevin is correct that the absence of lead in our environment was or is a “causal force” in crime rate declines:
- Nevin does not doubt that increased rates of incarceration contribute to the decrease in crime rates. See Exchange between Bill Otis and Rick Nevin at SL&P (November 1, 2013).
- Before he died, Professor James Q. Wilson, “one of the foremost authorities on crime” and the man who authored the “broken windows” theory of policing that was until recently followed by the New York City Police Department, believed that “greater incarceration can explain about one-quarter or more of the crime decline.” Id. By the way, Wilson’s estimate was put forth in an essay that forms the basis of my fourth caveat.
- Graham Farrell at Simon Fraser University in Canada tested the lead paint theory plus 14 other theories, including the theory of increased incarceration, to determine whether a particular theory adequately explained crime rate declines in the United States and elsewhere. After validity testing, he found that all but one theory flunked. Graham Farrell, Five Tests for a Theory of Crime Drop, Crime Science Journal (2013). The only theory that passed was a theory related to increased security practices of law abiding citizens (car alarms, for example). According to his profile, Farrell holds a BSc (Surrey) and PhD (Manchester) and is a Professor and Research Chair in Environmental Criminology at Simon Fraser.
- Near the end of his life, Professor Wilson wrote an an essay attempting explain declining crime rates and he gave a nod to Nevin’s research, and the research of many others. Wilson came to the conclusion that crime rate reductions were driven by various factors with a big change in the culture being the foremost explanation. James Q. Wilson, Hard Times, Fewer Crimes, Wall Street Journal (May 28, 2011) (“At the deepest level, many of these shifts, taken together, suggest that crime in the United States is falling—even through the greatest economic downturn since the Great Depression—because of a big improvement in the culture. The cultural argument may strike some as vague, but writers have relied on it in the past to explain both the Great Depression’s fall in crime and the explosion of crime during the sixties. In the first period, on this view, people took self-control seriously; in the second, self-expression—at society’s cost—became more prevalent. It is a plausible case.”) If “culture” was the ultimate explanation, “[c]ulture creates a problem for social scientists . . . We do not know how to study it in a way that produces hard numbers and testable theories. Culture is the realm of novelists and biographers, not of data-driven social scientists.” Id.
With these caveats in mind, let me finally get to the main thrust of this post. Roughly and simply speaking, here is Nevin’s reasoning:
Excessive lead exposure due to paint chips, car and truck fumes and otherwise can permanently drive down the IQ of a child and, at the same time, it can permanently reduce the child’s ability to control his impulses. Those twin harms tend to produce a criminal when the child grows up. Before lead reduction efforts by the government, crime rates rose, but after government lead reduction efforts, crime rates fell. That’s why you see reduction in crime rates for younger men, but no reduction, or even an increase, in crime rates for older men. Presumably, many of these older men have suffered the deleterious effect of excessive lead exposure when they were children, but the younger men have been spared.
Now, assume that Nevin’s reasoning is correct and the data support him. What should a judge do with this information? In my opinion, there are two things a judge should strongly consider if Nevin’s conclusions are correct.
First, particularly for drug and gun charges (that are often associated with violence), judges should be far more skeptical of the ability of older men (40 and above) exposed to lead as children to reform themselves in prison or conform their conduct to supervision when released. Therefore, increased incapacitation–longer prison sentences–for older men exposed to lead as children may be necessary plus additional supervised release time may be required to assure public safety. For example, instead of sentencing at the low-end of a Guideline range, an older man convicted of a drug or gun charge and exposed to lead as child might warrant a high-end prison sentence plus several years of additional supervised release as compared to that period the judge would have normally imposed.
Second, particularly for drug and gun charges, judges may wish to instruct the probation departments to seriously consider whether older men exposed to lead as children should be subjected to intensive supervision after they are released from prison. In other words, judges may wish to treat older men exposed to lead as children as posing an increased risk to violate the conditions of supervise release and insist that the probation departments act aggressively when supervising such a person in order to protect the public from the offender.
In summary, Nevin’s theory, if believed, may warrant tougher sentences and tougher and longer supervision for older men who commit drug or gun crimes, offenses that are often associated with violence, if the offender has been exposed to lead as a child. While Nevin may not have intended this result, it is a logical consequence of his research. And the increased risk of reoffense that Nevin’s theory implies, is precisely the type of risk factor J.C. Oleson, Senior Lecturer in Criminology and Director of Research, School of Social Sciences, University of Auckland, proposes that we consider and that I advocate. See here, here and here.