In Illinois the Supreme Court adopted the “Illinois Rules of Evidence.” They are found here. As a practitioner, it is nice to have what is supposed to be the law on evidence spelled out in a simple document.
I had the honor of attending the committee meetings and speaking about an objection to the way they were drafted on a certain technical issue. At the committee the people who drafted the rules indicated that they were not meant to change Illinois law on evidence. In other words, the rules are supposed to describe existing evidence law, not create new law.
Since the Supreme Court adopted the rules I was concerned about the “Learned Treatise” doctrine. Now for those of you who do not know what I mean by the learned treatise doctrine, in federal court and in Illinois prior to the adoption of the Illinois Rules of Evidence, a lawyer was allowed to impeach a witness who testified inconsistently with an authoritative document described in the law as a learned treatise. The theory is that if a book on the subject is authoritative and the witness testifies inconsistently, either the witness does not know what they are talking about or the witness may not be completely honest.