8-2501.Expert Witness Standards.

Article VIII. Evidence · Part 25. Expert Witness Standards · Last amended 2013 · Last verified July 20, 2026

In one sentenceSets four factors an Illinois court must apply to decide whether a witness qualifies as an expert on the medical standard of care at issue in a case.

Full Text of 735 ILCS 5/8-2501

Text size

In any case in which the standard of care given by a medical profession is at issue, the court shall apply the following standards to determine if a witness qualifies as an expert witness and can testify on the issue of the appropriate standard of care. (a) Relationship of the medical specialties of the witness to the medical problem or problems and the type of treatment administered in the case; (b) Whether the witness has devoted a substantial portion of his or her time to the practice of medicine, teaching or University based research in relation to the medical care and type of treatment at issue which gave rise to the medical problem of which the plaintiff complains; (c) Whether the witness is licensed in the same profession as the defendant; and

(d) Whether, in the case against a nonspecialist, the witness can demonstrate a sufficient familiarity with the standard of care practiced in this State.

Plain-English Summary

This section applies "in any case in which the standard of care given by a medical profession is at issue," directing the court to use four listed factors to decide whether a witness qualifies as an expert able to testify on the appropriate standard of care.

The factors are: (a) how the witness's medical specialties relate to the medical problem or problems and the type of treatment administered in the case; (b) whether the witness has devoted a substantial portion of his or her time to practicing medicine, teaching, or university-based research relating to the medical care and treatment type at issue; (c) whether the witness is licensed in the same profession as the defendant; and (d) in a case against a nonspecialist, whether the witness can show sufficient familiarity with the standard of care practiced in Illinois.

This is Illinois's own statutory gatekeeping test for standard-of-care expert testimony, operating on witnesses testifying to the standard of care in a case involving a medical profession, distinct from general rules governing expert opinion evidence.

Frequently Asked Questions

When does this section's expert-qualification test apply?

In any case where the standard of care given by a medical profession is at issue.

What four factors does the court weigh?

The relationship between the witness's specialties and the medical problem or treatment at issue; whether the witness has devoted substantial time to practicing medicine, teaching, or university-based research relevant to that care; whether the witness is licensed in the same profession as the defendant; and, for a nonspecialist defendant, whether the witness shows sufficient familiarity with Illinois's standard of care.

Must the expert witness be licensed in the exact same profession as the defendant?

The section lists that as one of the factors the court applies, so it's a required consideration, though the statute doesn't state how the four factors are weighed against one another.

Does the same-profession requirement change for a nonspecialist defendant?

The fourth factor adds a further inquiry for cases against a nonspecialist defendant: whether the witness shows sufficient familiarity with the standard of care practiced in Illinois.

Is this test limited to medical malpractice cases specifically, or is it broader?

Its trigger is any case where "the standard of care given by a medical profession is at issue," a category that includes but isn't necessarily limited to medical malpractice claims.

Amendment History

(Source: P.A. 97-1145, eff. 1-18-13.)

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 expert witness standard of caremedical malpractice expert qualification illinoisexpert witness same specialty illinois