25 ILCS 5/8

Whoever, being served with a subpoena to appear as a witness, or to produce any paper or document before either house of the General Assembly, or any committee thereof, or a joint committee of both houses, shall neglect or refuse to so appear, or to produce any such paper or document, or having appeared either with or without subpoena, shall neglect or refuse to be sworn or to testify, or to produce any papers or documents when lawfully required so to do, shall be guilty of a petty offense. This Section shall not be construed to affect the right of either house of the General Assembly to compel the attendance of any person as a witness, or to punish for disorderly or contemptuous behavior in its presence.