Illinois Criminal Evidentiary Rules: Expert Witnesses & Opinion Evidence

Illinois has finally adopted formal rules of evidence. Despite the declared intentions of the drafters, these rules do not fully harmonize with Illinois’ common law of evidence and the ad hoc modifications of those rules enacted by the legislature over the years. In Part 7 of his 7-part series entitled "Old Wine in a New Bottle: Illinois Law of Evidence and New Rules of Evidence for Criminal Defense," attorney Stephen L. Richards discusses the rules and case law governing the admission of opinion and expert testimony, including discussions of the Frye Rule, expert hearsay and exclusions of expert testimony.

Learning Objectives: 

I. Discuss the rules and case law governing the admission of opinion and expert testimony, including: 

• Frye Rule
• Expert hearsay
• Exclusions of expert testimony