(a) Any person may be made a defendant who, either jointly, severally or in the alternative, is alleged to have or claim an interest in the controversy, or in any part thereof, or in the transaction or series of transactions out of which the controversy arose, or whom it is necessary to make a party for the complete determination or settlement of any question involved therein, or against whom a liability is asserted either jointly, severally or in the alternative arising out of the same transaction or series of transactions, regardless of the number of causes of action joined.
2-405.Joinder of defendants.
Article II. Civil Practice · Part 4. Parties · Not amended since adoption on record · Last verified July 20, 2026
In one sentenceSection 2-405 sets broad rules for who may be joined as a defendant, protects uninterested defendants from unnecessary expense, and lets a plaintiff sue multiple defendants in the alternative when unsure who is liable.
Full Text of 735 ILCS 5/2-405
(b) It is not necessary that each defendant be interested as to all the relief prayed for, or as to every cause of action included in any proceeding against him or her; but the court may make any order that may be just to prevent any defendant from being embarrassed or put to expense by being required to attend any proceedings in which such defendant may have no interest.
(c) If the plaintiff is in doubt as to the person from whom he or she is entitled to redress, he or she may join two or more defendants, and state his or her claim against them in the alternative in the same count or plead separate counts in the alternative against different defendants, to the intent that the question which, if any, of the defendants is liable, and to what extent, may be determined as between the parties.
Plain-English Summary
A person can be made a defendant if they claim or are alleged to have an interest in the controversy, if they're needed for a complete determination of the questions involved, or if a liability is asserted against them — jointly, severally, or in the alternative — arising from the same transaction or series of transactions, no matter how many causes of action are joined.
Not every defendant has to be interested in every form of relief sought or every cause of action in the case. The court can enter whatever order is just to keep a defendant from being embarrassed or put to needless expense by having to take part in proceedings that don't concern them.
When a plaintiff isn't sure which of several people is responsible, the plaintiff may join two or more defendants and plead the claim against them in the alternative, either in one count or in separate counts against different defendants, so the court can sort out which defendant, if any, is liable and to what extent.
Frequently Asked Questions
Who can be joined as a defendant under this section?
Anyone alleged to have or claim an interest in the controversy, anyone necessary for a complete determination of the questions involved, or anyone against whom a liability is asserted jointly, severally, or in the alternative arising from the same transaction or series of transactions.
Does every defendant in a case have to care about every claim in it?
No. It isn't necessary that each defendant be interested in all the relief sought or every cause of action in the proceeding.
What protects a defendant who has little stake in parts of the case?
The court may enter any order that is just to keep that defendant from being embarrassed or put to expense by having to attend proceedings the defendant has no interest in.
Can a plaintiff sue multiple people when unsure which one is liable?
Yes. If the plaintiff is in doubt about who is entitled to provide redress, the plaintiff may join two or more defendants and plead the claim against them in the alternative, in the same count or in separate counts, so the court can determine which defendant, if any, is liable and to what extent.
Does the number of causes of action joined limit who can be made a defendant?
No. A person can be joined as a defendant regardless of the number of causes of action joined in the proceeding.
Amendment History
(Source: P.A. 82-280.)
Source & verification. Section text and amendment history are
reproduced verbatim from the Illinois Compiled Statutes, published by the
Illinois Compiled Statutes, Illinois General Assembly / Legislative Reference Bureau. Last verified July 20, 2026.
· Official source
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