Prosecutor Accountability through Data Transparency: Cook County Felony Case Processing Data Visualization

Why does Prosecutor Data Collection and Transparency Matter?

Transparency into prosecutorial decision-making is critical to ensuring that a prosecutor's office is accountable to the people it serves. For example, prosecutors can use data to assess whether current policies are being applied consistently, ensure that resources are appropriately focused for fair and equitable outcomes, and develop new policies that can address community concerns, such as racial disparities in the criminal legal system. Moreover, by making their data publicly available, prosecutors can empower the public to assess information about how cases are being processed within their communities and to better understand the role of the prosecutor in the criminal legal system.

Ultimately, prosecutor data transparency is essential for building community trust, ensuring the legitimacy of the prosecutorial function, and working towards a more just and equitable criminal legal system.

Data Collaborative for Justice (DCJ) Felony Case Processing Data Visualization Tool

The Cook County State's Attorney's Office (SAO), one of the nation's largest prosecutor's offices, recently released data on the handling of felony cases from 2011 to present. Using the Cook County felony case data, the Data Collaborative for Justice (DCJ), a non-profit criminal justice research organization, developed a data visualization that enables the public to analyze how cases prosecuted by the SAO move through the criminal legal system.

DCJ's Felony Case Processing Data Visualization Tool (see "Explore the Data" above) allows users to view outcomes at three key stages of the felony cases process:

  1. Felony Case Initiation - following an arrest, most cases go through a process known as felony review, in which the SAO makes a decision whether or not to prosecute. Cases may also be indicted by a grand jury or, in narcotics cases, filed directly by law enforcement.
  2. Case Disposition - Cases may be disposed in a variety of ways, including because a person pled guilty, was found guilty at trial, or the prosecutor decided not to proceed with the case.
  3. Sentencing - if a person is found guilty (either at trial or due to a plea), they can receive a variety of sentences, such as probation or prison.

To use the data visualization tool, select "Explore the Data" above. The Explore the Data page is organized into four tabs:

  • The Felony Case Processing Tree: This tab shows outcomes by charge type and allows users to see differences in outcomes by race and ethnicity/age/gender as well as filter cases by various timeframes.
  • The Felony Case Processing Table: This tab shows, for various charges types (e.g., homicides, narcotics cases), the outcomes by percent at each of three key stages of the felony case process (Felony Case Initiation, Case Disposition, Sentencing).
  • Changes to Charge Severity Graph & Table: This tab shows how frequently the severity of a person's charge increased or decreased between case initiation and case disposition.
  • Data & Definitions: This tab provides definitions of the outcomes presented by DCJ's Data Visualization Tool as well as additional details about the data.

DCJ is grateful for the assistance of the Cook County SAO in responding to DCJ's questions and inquiries during the development of the Felony Case Processing Data Visualization Tool. DCJ is particularly appreciative of the assistance provided by Matthew Saniie, SAO's Chief Data Officer, and Lisa Li, SAO Data Integration Analyst.

To better understand the case processing in Cook County, please refer to:
- Case Processing Overview in Cook County, a Flowchart
- Cook County State's Attorney Data Report of 2017, with Detailed System Term Definition
- Cook County State's Attorney Data Dashboard
- Cook County State's Attorney Open Data Guide
- Cook County State's Attorney Open Data Glossary

For the best experience, please visit this site in a wide screen desktop browser. If the tree gets cut off, please zoom out. Also if the visualization is difficult to view, please consider a different browser or clear the cache on the current browser.
Click on the nodes to examine the case processing points by race/ethnicity, gender, and age.

*** Race group 'Other' includes Asian and Native American.

These tables show the outcomes by percent for felony case initiated, disposition and sentence by the individual charges.

Changes to Charge Severity: Arrest to Disposition

As a person's criminal case moves through the criminal justice system, the severity of the crime(s) with which that person is charged may change. In Illinois, the most serious criminal charges are class X felonies ("Fel.X") followed by class 1 felonies ("Fel.1") through class 4 felonies and class A misdemeanors ("Mis.A") through class C misdemeanors. For instance, a person who is charged with a class 2 felony may have their case resolved as a less serious charge (a class 1 felony or lower) or a more serious charge (class 3 felony or higher). This could be due to a number of reasons, such as the identification of new evidence, the grand jury finding that the facts match a different severity than initially charged, the person agrees to a plead guilty to so long as the charge is reduced, or a jury finds a person guilty of a lesser charge.

How to read the graph and table

This graph and table provide two different visualizations of the same data. For the graph, on the left is the top charge when the case was initiated and on the right is charge at final disposition. For the table, on the left is the charge when the case was initiated and on the top is the charge at final disposition.

Data & Definitions

This tab provides additional details about the data and definitions related to the various stages of the Cook County felony case process presented in the Felony Case Processing Data Visualization Tool.

About the Data

DCJ's Felony Case Processing Tree groups felony charges into 14 broad charge categories (e.g., the charges of "possession of a controlled substance with intent to deliver" and "possession of a controlled substance" are grouped under the narcotics category). The charge categories are aligned with those the Cook County SAO created for its dashboard. DCJ's felony case processing tree includes 87.2% of the felony cases with top charges that fall into these 14 broad charge categories (charges such as "failure to register as a sex offender" that did not fit into the broad categories were excluded).

About the Felony Case Process and Related Definitions

Felony Case Initiation

Cook County SAO Felony Review

The SAO operates a Felony Review Unit ("FRU") 24 hours a day, 365 days a year. Law enforcement officers call FRU to seek approval of most felony charges. FRU may respond to law enforcement's request to file felony charges in a number of ways:

  • Approved: FRU approves charges, and the case is filed. These cases generally proceed to a preliminary hearing, which is a public hearing at which a judge determines whether there is sufficient evidence (a showing of "probable cause") to justify continuation of the case.
  • Rejected: Typically, FRU does not approve charges because the information presented does not satisfy the statutory requirements for a felony or because there is another evidentiary problem that will make proceeding on the case impossible.
  • Continued Investigation ("CI"): FRU may continue a case for further investigation if it appears there may be a basis for felony charges if additional information or evidence is collected. It is up to law enforcement to conduct additional investigation and decide whether to re-present a case to FRU.
  • Other: This category includes cases with a warrant issued, victim interviewed, and where information is not available about FRU's decision. It also includes cases where a law enforcement agency called FRU for advice and did not seek formal charges or called FRU regarding a juvenile case.

Grand Jury Indictment

  • Grand Jury Indictment: For some cases, the SAO may present charges to a grand jury made up of members of the public that hear evidence in secret. The grand jury will then determine whether there is sufficient evidence to issue an indictment against the defendant and require them to stand trial for the charges.

Directly Filed

  • Directly Filed: In narcotics cases and driving with suspended or revoked license cases, law enforcement may file charges without FRU approval. The SAO first engages with these cases at the bond hearing.

Case Disposition

After a case is filed, it can conclude in one of several ways:

  • Pled Guilty: The individual pleads guilty to the original charge or a less severe charge in the same charge category (e.g., a person originally charged with homicide pleads guilty to manslaughter).
  • Found Guilty: The individual is found guilty by a jury or a judge of the original or a less-serious charge(s).
  • Resolved by Another Charge: The final disposition was for another charge on the case rather than primary or top charge (e.g., a person originally charged with homicide and burglary ultimately pleads guilty to just the burglary).
  • Found Not Guilty: The individual is found not guilty of the crime(s) charged after a jury or bench trial.
  • Nolle Prosequi: The SAO decides not to proceed with a case.
  • Finding of No Probable Cause: Grand Jury or a judge finds no reasonable basis for believing a crime was committed (no "probable cause") and case is dismissed.
  • Other: This category includes cases that were dismissed after loss of a pretrial motion, where a person was found not guilty by reason of insanity, a mistrial was declared, due to the death of the individual charged, or cases where the individual failed to appear in court.
  • Pending Disposition For those cases that has not yet been disposed.


  • The Felony Case Processing Tree presents the disposition for the top charge for each case in the dataset but not for all of charges against an individual in a given case.


After a person is found guilty or pleads guilty, the individual is sentenced by the court. The most common sentence types for felony cases include:

Incarceration Sentences

  • Prison: A sentence of one year or more of incarceration, served in the Illinois Department of Corrections.
  • Jail: A sentence less than one year served in county jail; a sentence of felony probation may also include a requirement to serve time in the Cook County Jail.
  • Boot Camp: a program of military activities, physical exercise, labor-intensive work, and substance abuse treatment; successful completion of boot camp may lead to a sentence reduced to time served and placement on supervision.

Non-Incarceration Sentences

  • Probation: Mandatory compliance with court-ordered conditions for a specific period of time, monitored by a probation officer.
  • Conditional Discharge: Mandatory compliance with court-ordered conditions for a specific period of time, usually without the supervision of a case worker.
  • Second Chance Sentences: DCJ created this category of sentences to cover two types of sentences, Second Chance Probation and Supervision. For both of these sentence types, if an individual complies with all probation or court-ordered requirements, the case is dismissed without a conviction. Only misdemeanors are eligible for a Supervision sentence so this dataset reflects cases where an individual was originally charged with a felony but the case was disposed as a misdemeanor.


  • Includes all other sentences (e.g., inpatient mental health services).


  • The Felony Case Processing Tree includes a disposition category called "Missing Sentence" for those cases where the sentence information is missing from the data set.

Data definitions are mainly derived from Cook County SAO resources including data reports, a data dashboard, data guide and glossary:

DCJ thanks Tao Lin, a DCJ Data Scientist, for his work to develop and finalize the Felony Case Processing Data Visualization Tool. DCJ also thanks Quinn Hood, former DCJ Research Analyst, for his work on early versions of the tool.