In all cases of alleged medical or dental malpractice, where the plaintiff relies upon the doctrine of res ipsa loquitur, the court shall determine whether that doctrine applies. In making that determination, the court shall rely upon either the common knowledge of laymen, if it determines that to be adequate, or upon expert medical testimony, that the medical result complained of would not have ordinarily occurred in the absence of negligence on the part of the defendant. Proof of an unusual, unexpected or untoward medical result which ordinarily does not occur in the absence of negligence will suffice in the application of the doctrine.
2-1113.Medical malpractice - res ipsa loquitur.
Article II. Civil Practice · Part 11. Trial · Not amended since adoption on record · Last verified July 20, 2026
In one sentenceLets a medical or dental malpractice plaintiff rely on res ipsa loquitur, but has the judge, not the jury, decide first whether the doctrine even applies, based on common knowledge or expert medical testimony that the result doesn't ordinarily happen without negligence.
Full Text of 735 ILCS 5/2-1113
Plain-English Summary
This section applies to medical or dental malpractice claims where the plaintiff relies on res ipsa loquitur -- negligence inferred from the nature of the injury itself. The court, not the jury, makes the threshold call on whether the doctrine applies.
The court's determination can rest on either the common knowledge of laypeople, if that's adequate, or expert medical testimony establishing that the result would not ordinarily occur absent the defendant's negligence.
The standard for application: proof of an unusual, unexpected, or untoward medical result that doesn't ordinarily occur absent negligence is enough to invoke the doctrine.
Frequently Asked Questions
Who decides whether res ipsa loquitur applies in a medical malpractice case?
The court, not the jury.
What evidence can the court rely on to decide?
Either the common knowledge of laypeople, if adequate, or expert medical testimony.
What must the evidence show for the doctrine to apply?
That the medical result would not ordinarily occur absent negligence by the defendant.
Does this apply outside medical or dental malpractice?
No. This section addresses medical or dental malpractice claims specifically.
Is proof of an unusual or unexpected medical result enough on its own?
Yes. Proof of an unusual, unexpected, or untoward result that doesn't ordinarily occur absent negligence suffices to apply the doctrine.
Amendment History
(Source: P.A. 82-783.)
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: res ipsa loquitur illinois medical malpracticeillinois medical malpractice negligence inferencedental malpractice res ipsa loquitur illinois