80 Ill. Adm. Code 1.233
Evidence
Section 1.233 Evidence
a) Irrelevant, immaterial or unduly repetitious evidence shall be
excluded. The rules of evidence and privilege as applied in civil cases in the
circuit courts of Illinois shall be followed. However, evidence not admissible
under those rules of evidence may be admitted (unless precluded by statute) if
it is of a type commonly relied upon by reasonably prudent persons in the
conduct of their affairs.
b) Objections to evidentiary offers may be made and shall be
noted in the record.
c) Any party who has had evidence excluded may make an offer of
proof.