No person shall be disqualified as a witness in any action or proceeding, except as hereinafter stated, by reason of his or her interest in the event thereof, as a party or otherwise, or by reason of his or her conviction of any crime; but such interest or conviction may be shown for the purpose of affecting the credibility of such witness; and the fact of such conviction may be proven like any fact not of record, either by the witness himself or herself (who shall be compelled to testify thereto) or by any other witness cognizant of such conviction, as impeaching testimony, or by any other competent evidence.
8-101.Interested witness.
Article VIII. Evidence · Part 1. Interested Person as Witness · Not amended since adoption on record · Last verified July 20, 2026
In one sentenceA witness cannot be disqualified from testifying just because they have a stake in the case or a past criminal conviction, though both facts can be used to attack their credibility.
Full Text of 735 ILCS 5/8-101
Plain-English Summary
Illinois once followed the old common-law rule that a person with a financial or personal stake in a lawsuit, or a past criminal record, could not take the stand at all. Section 8-101 abolishes that rule for civil actions. Interest and conviction go to weight, not admissibility: a jury can hear the testimony and decide how much to trust it, but the witness is not barred from testifying in the first place.
The section preserves a narrow tool for the other side. A party's interest in the outcome, or a witness's prior conviction, can still be raised to impeach credibility. The statute also spells out how a conviction gets proved at trial: the witness can be made to admit it, another witness who knows about it can testify to it, or any other competent evidence can establish it.
This is the general rule that opens Article VIII's evidence provisions. It sets the baseline of full competency before the Code carves out its most notable exception, the Dead-Man's Act in Section 8-201, which restricts what an interested witness can say about conversations or events involving someone who has since died or lost legal capacity.
Frequently Asked Questions
Can a party to a lawsuit testify in their own case under Illinois law?
Yes. Section 8-101 removes the old disqualification for interested witnesses, so a party can testify even though they stand to gain or lose from the outcome.
Does a witness's criminal record keep them off the stand?
No. A conviction no longer disqualifies a witness under this section. It can be brought out to challenge the witness's credibility, but the witness still gets to testify.
How can a party prove a witness has a prior conviction?
The statute allows several methods: the witness can be compelled to admit it, another witness who knows of the conviction can testify to it, or the party can offer any other competent evidence of it.
Does Section 8-101 override the Dead-Man's Act?
No. Section 8-101 sets the general rule that interest does not disqualify a witness, but Section 8-201's Dead-Man's Act creates a specific, narrower restriction on interested witnesses testifying about conversations or events involving a deceased or legally disabled person.
Does this section apply in criminal cases?
The text refers broadly to actions and proceedings, but Article VIII of the Code of Civil Procedure governs civil evidence rules; criminal competency and impeachment rules are addressed separately under Illinois criminal procedure and evidentiary law.
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
Also known as: illinois witness competencyinterested witness illinoiscan a party testify in their own case illinoisprior conviction impeachment illinois civilwitness credibility illinois evidence