18-103.Pleadings.

This section lays out how a quo warranto case is pleaded once it's filed. The People of Illinois are deemed the plaintiff, and the adverse parties are defendants; the plaintiff's opening pleading is called a complaint. That complaint doesn't have to spell out every basis for the challenge — it can allege in general terms that the defendant exercises a claimed right without lawful authority and call on the defendant to show by what warrant they exercise it, joining multiple grounds in a single count if more than one exists.

When a citizen files on their own relation rather than through the Attorney General or State's Attorney, the complaint must allege that the citizen's request to those officials was refused or went unanswered, and that the court granted leave to file, tracking the requirements of Section 18-102.

The section also addresses competing claims to the same office, franchise, privilege, exemption, or license: all such claimants may be joined in a single complaint so their rights can be determined together, though the court may order separate trials when convenience requires it. As in mandamus and ne exeat practice, matters not germane to the proceeding's purpose can't be introduced by joinder, counterclaim, or otherwise.

Finally, the section gives the defendant a choice tied to how the plaintiff pleaded: if the plaintiff spelled out specific grounds, the defendant answers or moves against the complaint as in other civil actions; if the complaint used the general form, the defendant must disclaim or justify by answer, and if justifying, must set out the facts showing lawful authority. The plaintiff may then reply or move against that answer as in other civil cases.