This research brief examines trends in the number of individuals admitted to jail pretrial

or formally supervised under pretrial supervision in the community. It is likely that, when the PFA is implemented, the number and/or characteristics of those admitted to jail pretrial or supervised in the community under pretrial supervision will change. Given the limited amount of statewide data in Illinois regarding pretrial practices, understanding such trends in the volume and characteristics of defendants in pretrial detention and under pretrial supervision in the community is a starting point to estimating and planning for the potential impact of the PFA.

How Many Individuals Are Admitted to Illinois’ Jails?

In Illinois, the operation of jails is the responsibility of the elected Sheriff in each of Illinois’ 102 counties. However, a number of smaller counties do not operate their own jail, opting to house individuals in neighboring county jails and paying those counties a per-diem rate. In 2022, there were 11 counties that did not operate their own jail, while the remaining 91 counties operated jails that ranged in capacity from fewer than 10 detainees to more than 6,000 detainees. In most of Illinois’ counties, the jail also serves as the central booking facility for the county. This means that in most counties, all individuals subject to a custodial arrest are booked through the jail and, thus, admitted to the jail, if only for a short period time.

To examine the volume of people admitted into Illinois’ jails, we looked at two time periods: 2017-2019 (pre-COVID) and 2020-2021 (post-COVID).

Between 2017 and 2019, 298,151 people were admitted into jails statewide each year; and of those, 268,017 (90%) were being held pretrial (i.e., they were not yet convicted of a crime). By comparison, during the period from 2020 to 2021, 193,387 people were admitted into jails statewide each year, and 173,503 (90%) were being held pretrial. Thus, there was a 35% decrease in both the average annual number of total admissions and the number of people admitted pretrial into county jails between the 2017-2019 and the 2020-2021 periods.

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However, the large majority of those admissions continued to be individuals admitted pretrial.

How Long Are Individuals Held Pretrial in Illinois’ Jails?

Individuals who are admitted to jail pretrial can spend as few as 0 days in jail if they are simply booked and released or if they post bond the same day they are admitted. If not released immediately, they remain in jail until they can post a money bond (if a bond is set) or until their case is disposed. Between 2017 and 2019, individuals admitted pretrial into Illinois’ jails spent an average of 25 days in jail; by comparison, from 2020 to 2021, individuals admitted pretrial spent an average of 34 days in jail. Thus, while the annual number of people admitted to jail pretrial fell roughly 35% between 2017 and 2021, the average length of stay increased 36%. This change likely reflects a shift in the types of crimes for which individuals were being booked into jails across the state. As noted in our report on statewide arrests [4], we found that more serious crimes (i.e., those eligible for initial detention under the PFA) accounted for a larger share of the overall arrests in Illinois between 2020 and 2021.

In addition to these substantial increases in length of stay from 2017 to 2020, there were also differences in length of stay for those admitted into the Cook County jail relative to the rest of Illinois. From 2017 to 2019 individuals admitted to jail pretrial in Cook County spent an average of 51 days in jail, compared to just 15 days for individuals admitted pretrial in the rest of Illinois. Similarly, from 2019 to 2020, individuals admitted pretrial into Cook County jail spent an average of 76 days in jail, compared to just 19 days in the rest of Illinois. Part of this difference likely reflects differences in bond court practices in Cook County and the composition of criminal cases; but it also reflects the fact that, as described above, in most counties outside of Cook County the jails serve as the central booking facility for the entire county. This means that in most Illinois counties, everyone subject to a custodial arrest in the county is booked through the jail. In Cook County and a number of the suburban counties around Chicago, only those arrests that end up going through bond court and not released on their own recognizance are booked into the jail.

How Many People Are Held Pretrial in Illinois’ Jails?

Although the volume of people admitted to jail pretrial exceeded 268,000 individuals per year from 2017 to 2019, and exceeded 170,000 individuals per year in 2020 and 2021, the average daily population of pretrial detainees in Illinois is less than 18,300. Specifically, from 2017 to 2019, it is estimated that, on any given day, there were 14,258 to 18,201 people being held pretrial in jails across the state;

during 2020 and 2021, there were 13,827 to 15,994 people being held pretrial daily.

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Thus, while pretrial admissions fell 35% between 2017 and 2021, the increased length of stay among those pretrial detainees resulted in only a 2%-12% decrease in the average daily population of pretrial detainees in Illinois.

Although the existing statewide data regarding jail admissions lacks detailed information about the characteristics of those held in jail, some insights can be gained by examining data collected by the U.S. Department of Justice’s Bureau of Justice Statistics through their 2019 Jail Census. Of those held statewide in Illinois’ jails in 2019, most (89%) were male, 50% were Black, 33% were white, and 14% were Hispanic. Most (82%) were being held on felony charges, and most (89%) were being held pretrial. In terms of the racial composition of the jail population, in most jails the majority of detainees were white: in 70% of Illinois’ jails, 50% of more of those held were white. However, in the three largest county jails in the state—Cook, Winnebago and Will counties—50% or more of those in jail were Black.

How Many People Are Under Formal Pretrial Supervision in Illinois?

In addition to individuals being held pretrial in jail, people awaiting trial can also be formally supervised in the community under pretrial supervision. In addition to several counties not having jails, several counties also do not have pretrial supervision programs or staff. In fact, in 2020 and 2021, only 40 of Illinois’ 102 counties had individuals under formal pretrial supervision, up from 25 counties in 2017.

Between 2017 and 2021, the total number of adults under formal pretrial supervision increased 76%, from 11,038 individuals to 19,341 individuals. The large majority of individual (83%) were charged with felony offenses; the total number of adults under formal pretrial supervision for a pending felony case increased 72% between 2017 and 2021, from fewer than 10,000 statewide to nearly 16,000. Part of this increase was due to more counties establishing pretrial supervision capacities (from 25 to 40 counties), and part of the increase was a growing number of pending felony cases (up 32% from 2017 to 2021). Of the new cases placed on pretrial supervision in 2021, 20% had drug testing ordered, 14% were required to abide by a curfew, and 7% were under some form of electronic monitoring—either GPS, SCRAM, or electronically monitored curfew/home confinement—as part of their formal pretrial supervision.

In 2021, 48% of those placed on pretrial supervision in the state were Black, 35% were white, and 15% were Hispanic; most (82%) were male. As with the racial composition of those in jail, the racial characteristics of those on pretrial supervision also varied substantially across the individual counties that had formal pretrial supervision programs. For example, in Cook County 74% of those placed on pretrial supervision were Black, 15% were white, and 10% were Hispanic. Most—89%—were male.

How Many People Are in Custody or Under Pretrial Supervision in Illinois?

As described above, between 2017 and 2021, 13,675 to 18,201 people were held pretrial in jail on any given day. Among these individuals, 82% were facing felony charges and 18% were charged with misdemeanors.

Thus, between 11,213 and 14,924 people charged with felonies were in pretrial detention on any given day between 2017 and 2021. Similarly, it is estimated that between 2,461 and 3,276 people charged with misdemeanors were in pretrial detention on any given day during that same period.

Combining these jail estimates with the number of people on pretrial supervision and the number of pending cases provides a broad understanding of the degree to which individuals facing criminal charges are either in custody or on pretrial supervision.

Between 2017 and 2021, on an average day, roughly 17% of individuals facing felony charges were being held pretrial in jail, 18% were on pretrial supervision, and 65% were neither in jail nor being supervised.

As mentioned above, due to the limits of available statewide data, it is not possible to determine the nature of the charges (e.g., domestic violence charges, non-probationable forcible felonies, weapon offenses, etc.) of those in jail, on pretrial supervision, or not under custody/supervision. However, that is not to say that most of those charged with felony offenses did not spend some time in pretrial detention. Indeed, given the sheer volume of individuals booked through county jails pretrial—roughly 170,000 to 270,000 per year over the past 5 years—it is fair to say that most of those charged with a felony-level offense spent some time in pretrial detention. Indeed, previous research in Illinois found that 59% of all people convicted of a felony in Illinois received credit for time served in pretrial detention as part of their sentence.

Among those awaiting disposition on misdemeanor charges, a much smaller proportion are in custody or under formal supervision in the community. Between 2017 and 2021, it is estimated that less than 2% of those facing misdemeanor charges were held in jail on any given day, and less than 2% were on pretrial supervision.

Conclusion

Under current practices, roughly 173,000 people each year are admitted to jail pretrial in Illinois. Given the relatively short lengths of stay for most of these individuals, between 13,675 and 15,994 people are in jail pretrial on any given day. Further, as a result of changes in crime, arrests, and how cases matriculate through the justice system, the number of pretrial admissions to jail decreased between 2017 and 2021. During the time period examined, there also has been an increase in the number (and proportion) of defendants formally supervised in the community under pretrial supervision. This increase is due, in part, to an increased capacity for pretrial supervision, as the number of counties operating these pretrial programs has increased. It is likely that once the PFA is implemented, and the OSPS implements its services across the state, that a number of those individuals who have historically been held in pretrial detention (i.e., required to post bond to secure their release) will be placed on pretrial supervision.

Methodology

The analyses were produced by combing aggregate data collected by the Illinois Department of Corrections’ Jail and Detention Standards Unit with aggregate data collected by the Administrative Office of the Illinois Courts (AOIC). IDOC’s Jail and Detention Standards Unit (JDSU) collects aggregate data on a monthly basis from all county jails in Illinois, including the number of bookings for non-sentenced, sentenced, and weekend sentences and the total number of days each category of these bookings we held in jail. These monthly jail data collected by the JDSU were supplemented with additional information regarding the number of people in jail on the date of the annual inspections of each jail performed by the JDSU. Aggregate data for each jail collected through the U.S. Department of Justice’s Bureau of Justice Statistics (BJS) for 2019 through their Jail Census were also utilized to provide additional information to estimate specific characteristics of the jail populations. Finally, AOIC collects aggregate data on a monthly basis from all counties that have formal pretrial supervision programs including the number and characteristics of those placed on supervision and end of the month caseloads for felony and other types of cases. Data regarding the number of pending felony and misdemeanor cases at the end of each year were collected from AOIC’s Annual Statistical Report.