Depending on the type and scope of data you are able to collect, you should be able to determine the primary reasons that people end up in your local jail. These are the “drivers” of your local jail population. Your analyses will allow you to demonstrate which drivers are contributing most to jail population numbers, as well as which drivers have less of an effect. Understanding your local jail’s principal population drivers can help you to concentrate your efforts on policy changes that will have the greatest impact and can inform your arguments to other system actors or community advocates. Every jurisdiction will face unique issues, but below are some of the common trends in local jail populations that Vera researchers have observed in localities of various sizes across the country.

• Racial disparities in the jail population. Although not exactly a “driver” of local jail populations, racial disparities in the jail population should immediately raise major concerns across all areas of the local system. When there is an overrepresentation of a certain racial or ethnic group in the local system, this points to longstanding problems that may not be adequately addressed by focusing on jail population reduction alone. Eliminating racial disparities requires a conscious and deliberate framework to ensure that new policy changes do not inadvertently retain or exacerbate existing disparities.
• High pretrial incarceration rates. The historical purpose of bail was to facilitate the release of people pending trial, with conditions to ensure their appearance in court.^[]Digard and Swavola, Justice Denied, 2019, 1. Over time, many counties have started to treat pretrial incarceration as the norm and to order payment of money bail in nearly all cases. Although there are some narrow reasons to hold certain people in jail pretrial, such as risk of flight or threat to public safety, a significant portion of people in pretrial detention are there because they are unable to pay the bail that has been set by the judge.^[] One study estimates that 60 percent of people in jail nationwide are on pretrial detention, and close to a third of those are held due to inability to pay bail. John Mathews and Felipe Curiel, “Criminal Justice Debt Problems,” American Bar Association, November 30, 2019, https://www.americanbar.org/groups/crsj/publications/human_rights_magazine_home/economic-justice/criminal-justice-debt-problems/. High pretrial incarceration rates suggest that a county has an overreliance on money bail and a lack of alternatives to arrest and detention.
• People in jail on low bond amounts. Long stays in jail on low bond amounts indicate that people are being held in jail pretrial simply because they are too poor to pay for their release. This points to a county’s failure to include meaningful assessments of ability to pay during bail hearings, as well as the use of money bail in lieu of other forms of pretrial release for lower level charges.
• Arrests on warrants. Warrants can lead to jail population challenges because they require law enforcement to make an arrest and do not leave room for any additional discretion. This can drive up admissions to local jails.
  • Failure to appear warrants. Many courts immediately issue warrants for failure to appear if someone who is released pretrial fails to appear for a required court date. When a lot of people are in jail for failure to appear, this points to problems with communication regarding required court appearances, lack of resources to assist people in overcoming challenges in getting to court, or lack of mechanisms that allow people to reschedule their court dates.
    
  • Failure to pay warrants. Some courts issue warrants for nonpayment of fines and fees. When a significant number of people are in jail for nonpayment, this suggests that the jurisdiction has onerous policies of charging for the administration of justice, a lack of consideration for a person’s ability to pay fines and fees, and an unnecessary devotion of community resources toward jailing people who cannot afford comparatively small amounts of money.
• High admissions for certain charge categories. Localities should take note when one of the following charge categories is prevalent in their jail, especially when these categories show up frequently as the sole or most serious charge for a booking.
  • Charges related to substance use and possession: This indicates that many people in jail have treatment needs that will be better served in the community.
  • Municipal ordinance violations: This often points to a practice of criminalizing low-level infractions that are associated with homelessness or poverty, such as sitting outside, sleeping outside, or panhandling.
  • Low-level driving charges: This indicates a lack of diversion opportunities for minor driving offenses, as well as the criminalization of civil issues, such as driving with a suspended license—a problem more often linked to the inability to pay fines and fees than to dangerous driving.^[]See for example Chris Mai,The High Price of Using Justice Fines and Fees to Fund Government in Virginia (New York: Vera Institute of Justice, 2021), 4, https://perma.cc/B442-2HCV.
  • Other low-level and nonviolent charges: When a large portion of the jail population is there due to lower level, nonviolent charges, this points to a lack of diversion opportunities in the community and should motivate law enforcement and prosecutors to examine alternative methods of handling these cases.

• High admissions for technical violations of probation. Using incarceration as a penalty for technical violations of probation conditions—such as missing required check-ins, traveling outside of permitted areas, missing curfew, etc.—may point to (1) probation conditions that are more onerous or imposed for longer than necessary for public safety, or (2) a lack of graduated sanctionsthat help avoid the reliance on jail as a penalty.