Article I. General Rules · Not amended since adoption on record · Last verified July 20, 2026
In one sentenceRule 31 sets how seniority among Illinois Supreme Court justices is determined, mainly by length of continuous service.
Full Text of Ill. S. Ct. R. 31
Text size
Seniority among the judges of the Supreme Court shall be determined by length of continuous
service, but if the terms of two or more judges begin at the same time they shall determine the seniority as between or among themselves by lot, unless they are able to determine it by agreement.
Plain-English Summary
Rule 31 answers a narrow but practical question: who outranks whom on the Illinois Supreme Court. Seniority runs by length of continuous service. If two or more justices' terms started at the same time, they settle their relative seniority by agreement, or by lot if they cannot agree.
The rule matters beyond bragging rights. Rule 30 relies on this seniority order to decide who temporarily steps into the Chief Justice's role whenever that office is vacant, or whenever the sitting Chief Justice is absent or unable to serve.
Frequently Asked Questions
How is seniority determined among Illinois Supreme Court justices?
By length of continuous service on the court.
What happens if two justices' terms began on the same day?
They determine seniority between themselves by agreement, or by lot if they cannot agree.
Why does seniority matter on the Supreme Court?
Rule 30 uses seniority to determine who serves as acting chief justice when there is a vacancy or the Chief Justice is unavailable.
Is seniority based on age or service?
Service. Rule 31 measures seniority by length of continuous service on the court, not by a justice's age.
Does Rule 31 apply to any court besides the Supreme Court?
No, it addresses seniority specifically among the judges of the Supreme Court.
Committee Comments
This is former Rule 56 without change of substance.
Source & verification. Rule text, official Committee Comments, and
amendment history are reproduced verbatim from the Illinois Supreme Court Rules,
promulgated by the Supreme Court of Illinois. Last verified July 20, 2026.
· Official source
Also known as:supreme court justice seniorityacting chief justice illinoisjudicial seniority rulehow seniority is determinedrule 31 illinois supreme court