Illinois Statutes Chapter 735. Civil Procedure § 5/2-1105. Jury demand

(a) A plaintiff desirous of a trial by jury must file a demand therefor with the clerk at the time the action is commenced. A defendant desirous of a trial by jury must file a demand therefor not later than the filing of his or her answer. Otherwise, the party waives a jury. If an action is filed seeking equitable relief and the court thereafter determines that one or more of the parties is or are entitled to a trial by jury, the plaintiff, within 3 days from the entry of such order by the court, or the defendant, within 6 days from the entry of such order by the court, may file his or her demand for trial by jury with the clerk of the court. If the plaintiff files a jury demand and thereafter waives a jury, any defendant and, in the case of multiple defendants, if the defendant who filed a jury demand thereafter waives a jury, any other defendant shall be granted a jury trial upon demand therefor made promptly after being advised of the waiver and upon payment of the proper fees, if any, to the clerk.

(b) All jury cases shall be tried by a jury of 6. If alternate jurors are requested, an additional fee established by the county shall be charged for each alternate juror requested. For all cases filed prior to the effective date of this amendatory Act of the 98th General Assembly, if a party has paid for a jury of 12, that party may demand a jury of 12 upon proof of payment.