Eye on the Courts: Study Finds Mass Incarceration Not Behind Crime Drop



In the last few years there has been a strong pushback over what has become known as mass incarceration – where the U.S. has the highest incarceration rates in the world, and prison populations have risen even as crime rates have reached 40-year lows.

There is one school of thought that argues that mass incarceration is behind the drop in crime. However, that view has been increasingly challenged by those who argue that current policies are ineffective. The increase of prison population has been driven, not by an increase in dangerous criminals incarcerated, but by the failed war on drugs. Lengthy prison sentences put people away for a long time, but with many of them at an age where they are more likely to stop committing crimes.

It is this school of thought that has driven reform efforts such as AB 109, which seeks to change the way people are incarcerated, and now Prop. 47, which has changed the way people are charged in California for minor crimes.

Adding to a growing body of evidence is the research by the Brennan Center for Justice at NYU, which argues that long-standing policies that have led to the U.S. having the highest incarceration rate in the world, with some 2.3 million people behind bars, is not necessarily translated into less crime.

“If this is not bringing down crime, why are we incarcerating so many people? We’ve been able to identify more effective and less intrusive forms of policing that can also bring down crime,” Inimai Chettiar, director of the justice program at the Brennan Center, said in a telephonic news conference Thursday.

The study, “What Caused the Crime Decline?, “examines one of the nation’s least understood recent phenomena – the dramatic decline in crime nationwide over the past two decades – and analyzes various theories for why it occurred, by reviewing more than 40 years of data from all 50 states and the 50 largest cities.”

It concludes that “over-harsh criminal justice policies, particularly increased incarceration, which rose even more dramatically over the same period, were not the main drivers of the crime decline.”

“We find that incarceration had a much more limited effect on the drop in crime than previously thought,” Mr. Chettiar said. “Incarceration accounted for about 5 percent of the crime decline in the 1990s, and in the 2000s that drops to almost zero.”

On the contrary, the report finds “that increased incarceration has been declining in its effectiveness as a crime control tactic for more than 30 years. Its effect on crime rates since 1990 has been limited, and has been non-existent since 2000.”

More important were various social, economic, and environmental factors, such as growth in income and an aging population. One interesting finding was that “the introduction of CompStat, a data-driven policing technique, also played a significant role in reducing crime in cities that introduced it.”

The report concludes, “Considering the immense social, fiscal, and economic costs of mass incarceration, programs that improve economic opportunities, modernize policing practices, and expand treatment and rehabilitation programs, all could be a better public safety investment.”

This report issues three central findings:

  1. Increased incarceration at today’s levels has a negligible crime control benefit: Incarceration has been declining in effectiveness as a crime control tactic since before 1980. Since 2000, the effect on the crime rate of increasing incarceration, in other words, adding individuals to the prison population, has been essentially zero. Increased incarceration accounted for approximately 6 percent of the reduction in property crime in the 1990s (this could vary statistically from 0 to 12 percent), and accounted for less than 1 percent of the decline in property crime this century. Increased incarceration has had little effect on the drop in violent crime in the past 24 years. In fact, large states such as California, Michigan, New Jersey, New York, and Texas have all reduced their prison populations while crime has continued to fall.
  2. One policing approach that helps police gather data used to identify crime patterns and target resources, a technique called CompStat, played a role in bringing down crime in cities: Based on an analysis of the 50 most populous cities, this report finds that CompStat-style programs were responsible for a 5 to 15 percent decrease in crime in those cities that introduced it. Increased numbers of police officers also played a role in reducing crime.
  3. Certain social, economic, and environmental factors also played a role in the crime drop: According to this report’s empirical analysis, the aging population, changes in income, and decreased alcohol consumption also affected crime. A review of past research indicates that consumer confidence and inflation also seem to have contributed to crime reduction.



The key finding here dovetails on the 2014 report from the Brooking’s Institution’s Hamilton Project, which found that incarceration has “diminishing marginal returns.” In other words, “incarceration becomes less effective the more it is used.”

“As more low-level offenders flood prisons, each additional individual’s incarceration has, on average, a consecutively smaller crime reduction effect. The incarceration rate jumped by more than 60 percent from 1990 to 1999, while the rate of violent crime dropped by 28 percent. In the next decade, the rate of incarceration increased by just 1 percent, while the violent crime rate fell by 27 percent,” they write.

They are careful to note that “this report does not find that incarceration never affects crime. Incarceration can control crime in many circumstances. But the current exorbitant level of incarceration has reached a point where diminishing returns have rendered the crime reduction effect of incarceration so small, it has become nil.”

“We found at its current astronomical levels, increased incarceration lost its bite as a crime reducer,” said one of the study’s authors, Oliver Roeder.

Instead of one factor, the regression analysis model that the researchers run finds a combination of factors: increases in police officers, an aging population, a decrease in alcohol consumption, growth in income and decreased unemployment.

That dovetails with other research that suggests that demographic shifts rather than incarceration rates are driving much of the change in the crime population. That also suggests why additional incarceration would have marginal returns.

If you merely end up locking away people, are they less likely to commit crimes? You may catch a few that will be lifelong criminals, but you end up catching a lot of people in the net that would not have committed another crime. So, from a resource management perspective, you are spending scarce money, resources and prison beds on people who, statistically speaking, are unlikely to commit additional crimes.

Another interesting sub-finding was the effectiveness of crime analytics. CompStat is a comparative statistics policing method that was introduced in the 1990s by the NYPD and its been widely adopted nationwide.

The summary notes, “Through the authors’ research, CompStat emerged as one of the most consistent, easily identifiable, and widespread policing techniques employed during the time period under examination. CompStat is a police management technique — a way to run police departments — that was widely deployed in the nation’s cities in the 1990s and 2000s, starting in 1994 under New York City Police Department Commissioner Bill Bratton. Although departments use it differently, the general objective is the same: to implement strong management and accountability within police departments to execute strategies based on robust data collection to reduce and prevent crime. Departments and units deploy different specific tactics, including the ones listed above, to manage crime in neighborhoods. Notably, CompStat should not be conflated with these tactics. CompStat is not equivalent to broken windows, hot spots, or stop-and-frisk.”

The researchers found that CompStat policing contributed to about 10 percent of the nation’s crime decline.

That is not a stunning finding. After all, the use analytics has been used for anything from voter data to sports.

The research here is suggestive that the best approach to the reduction of crime is not to pump more money into incarceration, but rather a broad-based approach that gives police tools to fight crime more effectively, along with substance abuse programs, education and job training, among other factors.

—David M. Greenwald reporting


About The Author

David Greenwald is the founder, editor, and executive director of the Davis Vanguard. He founded the Vanguard in 2006. David Greenwald moved to Davis in 1996 to attend Graduate School at UC Davis in Political Science. He lives in South Davis with his wife Cecilia Escamilla Greenwald and three children.

Related posts

29 thoughts on “Eye on the Courts: Study Finds Mass Incarceration Not Behind Crime Drop”

  1. Davis Progressive

    this article largely confirms what most of us suspected – mass incarceration is not the cause of reduced crime rates.  amazing what happens when people systematically study an issue rather than operate under assumptions.

      1. Anon

        Yes, I have some skepticism as to how one measures whether incarceration or any other phenomenon is effective in reducing crime.  How is something like that even measured?

        What I will say though, is that I would like to see more emphasis on crime prevention at the earliest possible age, which means after-school programs, early intervention programs, etc.

        1. Barack Palin

          According to this article the Brennan Center for Justice uses funding from George Soros, that about says it all.

          “A new report from the National Center for Public Policy Research finds the Brennan Center for Justice – one of the country’s loudest opponents of voter integrity measures – to have a history of bias-driven research.
          The report also discloses that the Brennan Center has received millions in funding from George Soros.”


        2. David Greenwald Post author

          The simple answer is they stick a bunch of data into a multivariate regression equation and measure which changes in variables are most correlated with changes in incarceration. It’s far more complex than that because they are using a time-serious analysis and they are analyzing data at different levels of analysis – states and cities for instance. They analyzed a lot. For instance, “The authors chose 13 theories that were commonly cited in existing research and media reports to run in the state-level panel. Some factors such as technology, sentence lengths, other forms of policing, other criminal justice policies, or other social factors could also have contributed to the crime decline. Notably, technological advances in surveillance likely affected rates of burglary, robbery, and motor vehicle theft.”

          As someone who was trained in these methods, I have to say it is an impressive study in its breadth and what it looks at as possible factors.

        3. tribeUSA

          David–oops, meant to reply to your comment, not report it!

          I would think Principal Components Analysis (PCA) would also be useful in such complicated statistical investigations. Multi-regression has some serious associated issues of multicollinearity; pre-screening with PCA can help, however, with development of an appropriate multiregression model form.

        1. Barack Palin

          I’m saying that whenever right wing organization studies are posted on here they’re usually attacked for being just that, so the same should go for left wing studies and organizations.  In my opinion any study taken from this group it should be understood that it might be highly biased.

          From their mission statement:

          The Center’s work ranges from voting rights to campaign finance reform, from ending mass incarceration 

          1. David Greenwald Post author

            I could go through in painstaking detail and lay out to you why the research is solid regardless of the source. As I said just above, I was trained in regression analysis in graduate school. If you’re point is that you would prefer a more independent source have a whirl at the data – I won’t disagree with you. But from what I read, this looks solid. The impressive part is the breadth of their study and the amount of data they are able to analyze. I’m sure that won’t convince you. Let me know if you want me to bore you with the math.

      2. TrueBlueDevil

        Can we house the released criminals next to liberal organizations?

        I think it is Seattle that is using some of these new Eric Holder enforced policing strategies, and crime has gone up, substantially in some areas.

        1. Davis Progressive

          my only problem is rather than engaging on the issue, tbd is throwing partisan bombs and you’re calling people liberals.  i think this issue is kind of important and we should be discussing whether or not mass incarceration makes us safer, not whether or not we want to live next to a bunch of released inmates.

          to answer his crass question, when i was a defense attorney, some of my clients i would trust and others i wouldn’t.  that doesn’t mean the societal solution is to lock people away and throw away the key often for very mild offenses.  to me it means we should invest more money on the back end of the system rather than the front end.

    1. sisterhood

      So sick of every discussion turning into pot shots at the liberals. Rarely do others refer to conservatives unless they are baited by the verbal bullies on this website. Readers who stereotype “liberals” may be surprised that liberals have so many various opinions and some of them are in agreement with their critics. But you will never know us, as long as you try to find the least common denominator.

      I guess the problem with prison and jail overcrowding is all the fault of the Affordable Care Act and Illegals and global warming fake conspiracies and liberals and Obama and Holder. I’m glad I have ostracized at least one poster here. Far less b.s. to read.

    2. zaqzaq

      Nice article in LA Times on impact of Prop 47.  Theft crimes up by more than 10% and drug arrests down.  The point being that many individuals arrested for theft offenses are back out on the streets stealing again after Prop 47 when they would have been incarcerated prior to Prop 47.  This seems to contradict the study referenced in this article.  Also concerning is that officers have determined it is not worth their time to arrest individuals for possession further reducing any negative consequences for illegal drug use.   Drug users no longer motivated to participate in treatment because there is no consequence for not going into treatment.  One treatment program has only 27 of 62 beds filled as referrals from felony drug prosecutions dry up.  How is more money for drug treatment going to help if the users do not want to change and the court criminal justice system can no longer motivate them to go into treatment?

      Lock the doors and windows to your home, lock your car doors and bikes or your property is more likely to be stolen.

      Since I have never posted a link my apologies for failure if it does not work.


        1. David Greenwald Post author

          Or it is a period of adjustment where the system is going to shake out and settle down. When AB 109 came on line there was a slight bump up and then the crime rate returned to the downward trajectory.

        2. zaqzaq

          More likely the beginning of a trend of increased theft due to the limited sanctions available to law enforcement.  More alarming than the increase in theft is the reduction in individuals participating in court ordered treatment.   Do we have a drug court in this county?  If we do it would be interesting to compare the number participating in the program pre and post prop 47.

          1. David Greenwald Post author

            We have a drug court in this county. Numbers were reportedly down. I would argue that Prop 47 is only a first step, now it is time for the system to adjust. We now need to invest in new programs. If we simply reduce sentences and don’t replace the punishment with new services, then critics are probably correct that crime in the short term will rise.

  2. Barack Palin

    What we have here is a liberal study backed by liberal money from a liberal organization with the liberal agenda of ending mass incarceration.  So are the results any surprise?

    1. Miwok

      As more low-level offenders flood prisons, each additional individual’s incarceration has, on average, a consecutively smaller crime reduction effect.

      This assumes there is a finite number of criminals? What an assumption to make.

      I think many of these people don’t want to see their drug dealer go to jail, or their kid.

      All I know is you cannot park a bicycle, leave door unlocked, or leave a car very long without someone testing the door to see if it is unlocked, even in your own driveway. Crime? Down? Not for me, or for you.

  3. Tia Will

    If one believes the left wing organization’s study.”

    I do not think that one should base their belief in any study on the political affiliation of the authors, but rather on the design, scope, breadth, methodology and consistency of the study with previous works as well as its reproducibility. While I have no formal training in the analysis of the validity of studies, my partner does and is supportive of David’s take on this study.

    The other erroneous assumption being made here by the “liberals are all unreliable” school of thought, is that liberals all think the same. As an avowed liberal, I can guarantee you that there is not unanimity of thought about our justice system and the complexities of incarceration even within my house, let alone in the “left wing” as a whole. My partner who works in a related capacity is much more objective about the  probability that a given individual will commit another offense. I, on the other hand, can be swayed by my personal abhorrence of the crime itself rather than the probability that the person will offend again. His approach using objective, data driven information is obviously superior than my “oh, my gosh” fear driven approach. Unfortunately, many of us are unwilling to look past our own fears to determine what actually makes us safer, rather than what merely makes us feel safer. The two are often not the same.

    1. Davis Progressive

      to dovetail on this point.  first, they describe themselves as: “Part think tank, part advocacy group, part cutting edge communications hub, we start with rigorous research.”  naturally a good policy group is only as good as their research.  the authors in this are an economic phd from university of texas, a person with a jd from georgetown, among others.  i would prefer to see work like this peer reviewed, as i lack the ability to cut through potential methodological flaws, but it would have been much more interesting to have had a discussion on the content of the work rather than a discussion over whether or not it was a “liberal” piece and therefore let’s discount it as a whole.  but apparently the combatants were not interested in a real discussion and left.

      1. Barack Palin

        Shall I pull up the many posts where liberals on here poo-pooed websites and studies for being right wing organizations, or funded by the Koch Bros. or oil companies or plastic bag manufacturers, etc.?

Leave a Reply

X Close

Newsletter Sign-Up

X Close

Monthly Subscriber Sign-Up

Enter the maximum amount you want to pay each month
Sign up for