Evidence-Based Solutions to the Mass Incarceration Crisis: Neuroscience and Cash Bail

Mass incarceration is a public health crisis with particular relevance to the neuroscience community. Much of our work as neuroscientists revolves around the criminal justice system, including mental illness, adolescent development, addiction, and educational attainment. In our efforts to progress society by pushing the boundaries of human knowledge, we urge the neuroscience community to consider incorporating efforts to ensure that existing science is harnessed to affect solutions. The neuroscience field has long offered insight on the effective and humane treatment of those most adversely affected by the criminal justice system (e.g., the continuation of brain development into our mid-20s and application of such findings to the trying of children as adults – a common practice in California), and we must continue to advocate for the incorporation of science in the criminal justice system.

One surprising driver of the mass incarceration crisis is pretrial detention, which refers to the detainment of those accused of a crime before they receive their trial. 95% of the growth in the U.S. jail population over the last 20 years is due to pretrial detention [1], which is in turn driven by the cash bail system. Cash bail is a term many of us have likely heard, but understanding the context of its operation is critical to understanding how the mass incarceration crisis has developed. Briefly, a pretrial defendant is assessed by a judge (sometimes with input from prosecutors, probation officers, etc.) on whether they pose a threat for (A) flight (not showing up to trial) or (B) danger to society. Those who are not a threat are offered freedom until their trial, for a fee. Inability to pay that fee deems a defendant a liability to return for trial, so they are placed in pretrial detention (usually in local jails that can actually pose greater dangers to health due to lack of comprehensive medical services, especially for mental illness [2-4]). Thus, the cash bail system conflates wealth with accountability and effectively funnels low-income and marginalized populations into our jails. Cash bail is indefensible, and the U.S. is one of only two countries in the world to operate on what is a transparently biased and discriminatory system.


“Thus, the cash bail system conflates wealth with accountability and effectively funnels low-income and marginalized populations into our jails”


Cash bail is unjust. So is much else in our society. Why else should we care? Cash bail is wildly inefficient: it compromises public health without a justifiable preservation of public safety. The disruption to one’s life and its effects on physical and mental health are severe [3-11]. All of these amplify health, social, and financial burdens associated with recidivism [4, 12-17]. Imprisonment for even just three days increases the chance of committing another crime and perpetuates the cycle of incarceration [17]. See “The Costs of Cash Bail” for an assessment of all the inefficiencies and inequalities of cash bail.

Cash bail continues to prevail in California. However, there are a variety of promising alternatives and data points:


  • Diversion to appropriate addiction and mental health professionals effectively reduces the burden on the criminal justice system while getting people the help they need [18 ] but is vastly underused in LA County [19].

  • Restorative, community-based interventions have been shown to be highly successful [20-24].

  • Simple behavioral nudges, such as text message reminders and transportation to court appearances, effectively and inexpensively increase court appearances [24-29].

  • On the other hand, interventions that prioritize discipline and surveillance have been shown to be largely ineffective [20,21] and can elevate incarceration rates through petty technical violations [30,31]. They also can cause financial strain through mandates for things like courses that impede employment (who can leave work at 1:00 pm on a Tuesday for a mandatory course that, if not completed, lands them back in jail?) and expensive ankle monitors (sometimes up to $900!) [32].

  • Prioritizing pretrial services that emphasize restorative, community-oriented solutions would create thousands of jobs and is projected to save billions annually (in 2014, an estimated $10 billion with a pretrial detainment rate of 40%, and $20 billion at 10% [33]).


Our current system of pretrial detention is on the ballot this November and presents an opportunity to address this urgent issue. As neuroscientists and medical researchers, we are invested in improving health outcomes for vulnerable, system-impacted populations (i.e., children, the mentally ill, etc.), and we must recognize the value that evidence-based approaches to addressing pretrial detention will have for public health. Shifting towards pretrial release over detainment is the only option that ensures equity and avoids the health dangers of imprisonment, as well as beginning to move away from perpetuating the cycle of incarceration and generational trauma. In fact, places that have prioritized pretrial release have not seen an increase in court absences, violent crimes, or arrests (seriously, it doesn’t [7,34-40]). In Santa Clarita County, 95% of released defendants appear for court and only 1% are rearrested while awaiting trial [41].


“As neuroscientists and medical researchers, we are invested in improving health outcomes for vulnerable, system-impacted populations”


California’s cash bail system is socioeconomically & racially discriminatory and dangerous to physical & mental health. Unfortunately, the measures proposed in SB10 (Prop25) may be even worse [42]. The bail reforms proposed on the ballot this November in Proposition 25 (previously Senate Bill 10) are not predicted to reduce pretrial detention [35,37,43-46]. Prop 25 relies on risk assessment tools that algorithmically determine risk of fleeing or committing a crime. However, an algorithm is only as good as its data, and this data is known to discriminate based on race and socioeconomic status [37,45,47-57]. The measures in Prop 25 are projected to be just as discriminatory as our current system. Even the ACLU has revoked their support [58]. See “Inefficiencies and Dangers of Actuarial Risk Assessment Tools” for all the reasons risk assessments are insufficient.


As scientists, we are trained to recognize the good data from the bad, and we can recognize that these solutions are sloppy. When thinking about designing a pretrial system, there do exist efficient and thoughtful solutions that also happen to be simple and cost-effective. More research is needed, including longitudinal analyses and randomized control trials [59], but the research that currently exists can still be put to use. Pretrial detention is a large but singular piece to addressing the mass incarceration issue. We have a responsibility to voice our support for solutions that will make for a just, evidence-based, safer, and healthier society.


“The bail reforms proposed on the ballot this November in Proposition 25 (previously Senate Bill 10) are not predicted to reduce pretrial detention”


Written by Zoe Guttman and Yuki Hebner.
Edited by Elizabeth Burnette and Holly Hake.

The writers and editors encourage California residents to vote NO on CA Proposition 25.
Learn more about the science of cash bail in this article.


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  • Zoe Guttman

    Zoe received degrees in Neural Science and Psychology from New York University before moving to Los Angeles to pursue her PhD in Neuroscience at the University of California, Los Angeles. In the lab of Dr. Edythe London, she combines cognitive neuroscience and behavioral economics (Neuroeconomics) to investigate decision-making under risk and uncertainty in both healthy people and those with addictive disorders. She uses neuroimaging methods (fMRI, PET), economic tasks, and computational models to better understand why people make less-than-ideal choices in environments of uncertainty. She is a co-founder of the Science Policy Group at UCLA and enthusiastic about science policy and communication.

Zoe Guttman

Zoe Guttman

Zoe received degrees in Neural Science and Psychology from New York University before moving to Los Angeles to pursue her PhD in Neuroscience at the University of California, Los Angeles. In the lab of Dr. Edythe London, she combines cognitive neuroscience and behavioral economics (Neuroeconomics) to investigate decision-making under risk and uncertainty in both healthy people and those with addictive disorders. She uses neuroimaging methods (fMRI, PET), economic tasks, and computational models to better understand why people make less-than-ideal choices in environments of uncertainty. She is a co-founder of the Science Policy Group at UCLA and enthusiastic about science policy and communication.