Monday, January 16, 2017

Incarceration rates and crime: A counter-intuitive relationship

The lock-em-up logic of mass incarceration holds that prison expansion keeps more criminals off the street and therefore reduces crime. But that's an hypothesis, not a fact. Luckily, differing incarceration policies among states in recent years have supplied a natural experiment to test the theory, which turns out to be full of holes. In fact, a new analysis from Pew analyzing the state-by-state data found that jurisdictions which reduced incarceration most saw higher drops in crime rates.

Crime has declined across the western world and throughout the United States since the 1990s, but at the state level there have been variations. From 2010 to 2015, according to Pew, 35 states saw reductions in incarceration rates while 44 states saw reductions in violent and property crime.

Digging more deeply, the states which reduced incarceration most saw higher crime reductions. "In the 10 states with the largest imprisonment declines, the crime rate fell an average of 14.4 percent, compared with 8.1 percent in the 10 states with the biggest growth in imprisonment."

Of the 10 states with the largest imprisonment reduction, Texas' rate remained by far the highest. Still, Texas' imprisonment rate declined 12.9 percent from 2010 to 2015, emblemized by the closure of three prison units, while our crime rate declined 23.3 percent.

Pew offered this understated conclusion: "The lack of a consistent relationship between the crime and imprisonment trends reinforces the findings of the National Research Council and others that the imprisonment rate in many states and the nation as a whole has long since passed the point of diminishing public safety returns." Grits would put the lesson from their research more plainly: The evidence shows incarcerating fewer people does not correlate with increased crime and in fact, correlates more strongly with larger crime reductions.


Anonymous said...

My guess is that there are way too many variables for anyone to definitively establish any correlation between decreased incarceration rates and crime reduction. Just a hunch, but I suspect a much easier "cause and effect" correlation to establish would be between job rates and crime. The more time people spend working, the less likely they're drinking, doing drugs or otherwise getting into trouble. Men who are employed are also more likely to wind up in stable, lasting relationships with women (marriage, kids, etc.) which is also a disincentive to criminal behavior. On the other hand, when unemployment rates are up, there are large segments of society which have a lot of free time on their hands and find themselves in difficult economic circumstances. This in turn results in alcohol and drug use, broken family relationships and crime. I would be curious to see a study that analyzed crime rates, incarceration rates and job rates together. Maybe that research is already out there.

Gritsforbreakfast said...

Agreed, we can't establish causation for lower imprisonment and crime rates. But we can say that there IS NO comparable correlation between higher imprisonment and lower crime rates.

IOW, this shows the tuff-on-crime "more incarceration protects us more" meme is false on its face. We can't prove definitively that lower incarceration caused lower crime. But we can say for sure that the argument that higher incarceration makes us safer is simply false. It's not a correlation/causation question - the correlation isn't even there.

Anonymous said...

One thing is for certain, those individuals who are incarcerated are not committing crime outside of prison during the time they are locked up.

Gritsforbreakfast said...

Except they don't stay locked up, 10:47, there's just a lot of churn. 70k leave every year; a like number enters.

Anonymous said...

When will people realize that the objective of this blog, and its esteemed leader, is NOT anti-LE or pro-criminal?
It is pro-public safety.
Increased incarceration for non-violent crimes only endangers the public. These incarcerated offenders DO get released, and many give up on their job search after weeks, or months, of being told "Not just no, but hell no!". What do you think they are going to do? Go to church and pray for some food? No, they will commit more crimes, and care less about those they hurt in the process, because it is clear nobody gives a damn about them.

Thanks again, Scott, for all your hard work.