(735 ILCS 5/2-1106) (from Ch. 110, par. 2-1106)
    Sec. 2-1106. Peremptory challenges - Alternate jurors. (a) Each side shall be entitled to 5 peremptory challenges. If there is more than one party on any side, the court may allow each side additional peremptory challenges, not to exceed 3, on account of each additional party on the side having the greatest number of parties. Each side shall be allowed an equal number of peremptory challenges. If the parties on a side are unable to agree upon the allocation of peremptory challenges among themselves, the allocation shall be determined by the court.
    (b) The court may direct that 1 or 2 jurors in addition to the regular panel be impanelled to serve as alternate jurors. Alternate jurors, in the sequence in which they are ordered into the jury box, shall replace jurors who, prior to the time the jury retires to consider its verdict, become unable to perform their duties. Alternate jurors shall be drawn in the same manner, have the same qualifications, be subject to the same examination and challenges, take the same oath, and have the same functions, powers, facilities, and privileges as the principal jurors. An alternate juror who does not replace a principal juror shall be discharged at the time the jury retires to consider its verdict. If alternate jurors are called each side shall be allowed one additional peremptory challenge, regardless of the number of alternate jurors called. The additional peremptory challenge may be used only against an alternate juror, but any unexercised peremptory challenges may be used against an alternate juror.
(Source: P.A. 83-707.)