The Illinois Jury System: How Juries Are Selected and How Duty Works

Illinois jury service operates at the intersection of constitutional mandate and statutory procedure, shaping the outcome of thousands of civil and criminal cases each year across the state's 102 counties. This page covers how jurors are summoned, screened, and seated in Illinois courts; what obligations apply once a person receives a summons; and how the selection process differs between civil and criminal proceedings. The Illinois jury system is governed primarily by the Illinois Code of Civil Procedure (735 ILCS 5/2-1100 et seq.) and the Illinois Code of Criminal Procedure (725 ILCS 5/Art. 115), with supplementary rules issued by the Illinois Supreme Court.

Definition and Scope

A jury in Illinois is a body of impartial citizens convened to determine facts in a legal proceeding. Two principal jury types exist within the state court system:

• Petit jury: A trial jury that evaluates evidence and returns a verdict. In criminal cases, a petit jury consists of 12 jurors (725 ILCS 5/115-4). In civil cases, the default is 12 jurors, but parties may stipulate to fewer under 735 ILCS 5/2-1105.
• Grand jury: A body of 16 members that reviews evidence in felony criminal matters to determine whether probable cause exists to indict. Grand juries operate under 725 ILCS 5/112 and are not used in civil proceedings.

Jury service is a constitutional obligation under Article I, Section 13 of the Illinois Constitution of 1970, which preserves the right to trial by jury. The Illinois Supreme Court Rules — particularly Rule 433 governing jury selection — provide procedural standards that apply statewide, though each of the 24 judicial circuits may issue supplementary local requirements.

The broader legal framework governing jury rights connects to Illinois due process protections and sits within the structural overview described in the Illinois court system structure reference.

How It Works

The Illinois jury selection process proceeds through defined phases:

1. Compilation of the master jury list: Each county compiles its jury pool from voter registration records and, in most circuits, from driver's license and state ID records maintained by the Illinois Secretary of State. This dual-source approach is authorized under 705 ILCS 305/2.

2. Summons issuance: Prospective jurors receive a written summons from the circuit clerk of their home county. Illinois law prohibits employers from penalizing employees for responding to a summons (705 ILCS 310/10.1).

3. Qualification screening: To serve, a person must be a U.S. citizen, at least 18 years of age, a county resident, able to understand English, and free from felony conviction (unless civil rights have been restored under 730 ILCS 5/5-5-5).

4. Voir dire examination: Attorneys and, in some circuits, the presiding judge question prospective jurors to identify bias. Attorneys may exercise an unlimited number of challenges for cause — removal based on demonstrated partiality — and a fixed number of peremptory challenges, which require no stated reason. In capital cases, each side receives 14 peremptory challenges (725 ILCS 5/115-4(e)); in standard felony trials, each side receives 7.

5. Empanelment: Once the required number of jurors and any alternates are seated and sworn, trial proceeds. Alternates replace deliberating jurors only if a seated juror becomes unable to continue before deliberations conclude.

The full procedural landscape for criminal proceedings — including how jury trials interact with plea negotiations — is addressed in the Illinois legal procedure: criminal cases reference.

Common Scenarios

Criminal felony trial: Twelve jurors are seated. A unanimous verdict of guilty or not guilty is required (725 ILCS 5/115-4(n)). If jurors cannot reach unanimity, the result is a hung jury, which may lead to retrial or dismissal at the prosecution's discretion.

Civil jury trial: Under 735 ILCS 5/2-1202, a civil verdict requires the agreement of at least 10 of 12 jurors — a meaningful contrast to the criminal unanimity requirement. This lower threshold reflects the preponderance-of-evidence standard applied in civil matters. Civil procedure rules are further detailed in the Illinois legal procedure: civil cases reference.

Grand jury proceedings: A grand jury of 16 is drawn from the same county pool. Proceedings are conducted in secret, without defense counsel present. A minimum of 9 grand jurors must concur to return an indictment (725 ILCS 5/112-6).

Hardship exemption requests: A summoned juror may request a postponement or exemption based on financial hardship, medical incapacity, or caregiving obligations. Circuit clerks evaluate requests under locally adopted guidelines. No statewide uniform standard sets a specific income threshold for hardship claims.

Decision Boundaries

Scope of this reference: The information here pertains to jury service in Illinois state courts — the circuit courts operating under 705 ILCS 305 and the Illinois Supreme Court's supervisory jurisdiction. Federal jury service in the Northern, Central, and Southern Districts of Illinois is governed separately by the Jury Selection and Service Act of 1968 (28 U.S.C. § 1861 et seq.) and the local rules of each U.S. District Court — not Illinois state statutes.

What this page does not cover: Jury practices in Indiana, Wisconsin, Missouri, Iowa, or Kentucky; tribal court proceedings within or adjacent to Illinois; federal grand jury procedures; or appellate review standards for jury verdicts. Appeals arising from jury determinations are addressed in the Illinois appeals process overview reference.

Interaction between state and federal standards: The Sixth and Seventh Amendments to the U.S. Constitution establish federal floors for jury rights in criminal and civil cases, respectively. Illinois constitutional and statutory provisions may extend — but may not diminish — those federal baselines. The relationship between state and federal frameworks is examined in the regulatory context for Illinois legal system and in the Illinois interplay: state and federal law reference.

For a broad orientation to Illinois legal services and how to navigate the state's legal landscape, the Illinois Legal Services Authority provides the primary reference index for this domain.

References

• Illinois Code of Civil Procedure — 735 ILCS 5/2-1100 et seq. (Illinois General Assembly)
• Illinois Code of Criminal Procedure — 725 ILCS 5/Art. 115 (Illinois General Assembly)
• Illinois Jury Act — 705 ILCS 305 (Illinois General Assembly)
• Illinois Courts — Supreme Court Rules, Rule 433
• Illinois Constitution of 1970, Article I, Section 13 (Illinois General Assembly)
• Jury Selection and Service Act of 1968 — 28 U.S.C. § 1861 et seq. (U.S. House of Representatives Office of Law Revision Counsel)
• [Illinois Supreme Court (illinoiscourts