Sentencing Length and Recidivism: A Review of the Research

We previously announced a working paper, Sentence Length and Recidivism: A Review of the Research, in May 2021 and announced an update last June. We are pleased to announce that the review has now been published in a peer-reviewed journal, Federal Sentencing Reporter, in the October issue. (Vol. 35, No. 1) The permanent link to the published version is https://doi.org/10.1525/fsr.2022.35.1.59. The paper is also available on CJLF’s website.

Here is the abstract:

In response to prison overcrowding concerns in recent years, many U.S. officials have undertaken efforts to reduce sentence lengths for certain crimes. However, it is unclear how these changes affect recidivism rates. Among the research on incarceration and recidivism, the majority of studies compare custodial with noncustodial sentences, while fewer examine the impact of varying incarceration lengths. This article reviews the research on the latter. Overall, the effect of incarceration length on recidivism appears too heterogeneous to draw universal conclusions, and findings are inconsistent across studies due to methodological limitations. For example, many study samples are skewed toward people with shorter sentences while others include confounds that render results invalid. Of the studies reviewed, some suggested that longer sentences provide additional deterrent benefits in the aggregate, though some studies also had null effects. None suggested a strong aggregate-level criminogenic effect. We argue that a conclusion that longer sentences have a substantial criminogenic effect, large enough to offset incapacitative effects, cannot be justified by the existing literature.

That last sentence is important.

When Los Angeles District Attorney George Gascón announced that his office would no longer seek any sentence enhancements, he gave this justification for the policy: “While initial incarceration prevents crime through incapacitation, studies show that each additional sentence year causes a 4 to 7 percent increase in recidivism that eventually outweighs the incapacitation benefit.” (Special Directive 20-8, emphasis added.) If by “studies show” he meant that the body of research literature as a whole shows that, his assertion is false. He cited a single, outlier, cherry-picked, unpublished manuscript with that finding, but that hardly justifies his misleading statement about what “studies (plural) show.”

Incarceration of people who have committed serious crimes prevents almost all of them from committing further crimes against people on the outside for the duration of their incarceration.* In addition, one “treatment” that we know works for violent crime is age. While almost all criminals will be released eventually, the violent ones who are released in middle age or later will, on average, be considerably less violent than they would be if they were released while still young. These crime-reducing effects of long sentences are undeniable. Gascón’s claim that they are outweighed by a powerful recidivism-reducing effect of long sentences is not only not supported by the literature, it is contradicted by it. A large number of studies over many years have shown that the effect of sentence length on recidivism is not strong in either direction.

Locking up violent criminals saves innocent people from being robbed, raped, or murdered. The claimed offset from substantially increased recidivism does not exist.


Some readers may be wondering why it took so long to get this article published. A large part of the reason is the length. A thorough review of this many studies takes a lot of space. Few journals in this field are willing to publish an article this long. We thank Doug Berman and all the folks at FSR for accommodating the needed length of this article.


* In-prison crime is, of course, a matter of serious concern. Further, there are a few criminals with sufficient outside connections to commit crimes by proxy on the outside. Even so, people on the outside are undeniably safer overall when violent criminals are locked up.