705 ILCS 25/11
Each branch of the appellate court may grant relief by mandamus to cause a proper record to be duly certified, or made and certified, or to cause any other act to be done which may be necessary to enforce the due administration of justice in all matters, actions or proceedings, which could or might by appeal or in any other lawful manner, be brought within the court's jurisdiction; upon complaint filed, the clerk of the branch appellate court shall issue summons, and like proceedings shall be had as in other cases of mandamus. The appellate court may also grant relief by certiorari and all other relief not prohibited by law, which may be necessary to enforce the due administration of justice in all matters within the appellate court's jurisdiction. Such process shall run in the name of the People of the State of Illinois, and bear test in the name of the presiding judge of the division of the branch appellate court from which it may issue, be signed by the clerk, dated, when issued, sealed with the seal of the court, and made returnable according to law.
705 ILCS 25/11