Illinois Statutes Chapter 25. Legislature § 5/4. Oaths

§ 4. The presiding officer of each house, and the chairman, or any member of any committee appointed by either house, or of a joint committee appointed by the two houses of the General Assembly, may administer oaths and affirmations to witnesses called before such house or committee for the purpose of giving evidence touching any matter or thing which may be under the consideration or investigation of such house or committee.