25 ILCS 5/6
Any person may be compelled, by subpoena, to appear and give testimony as a witness, and produce papers and documents before either house or a committee thereof, or a joint committee of both houses. The subpoena shall be signed by the presiding officer of the house or the chairman of the committee before whom the witness is to appear, and may be served in the same manner as subpoenas from courts. But the testimony of a witness examined and testifying before either house of the General Assembly, any committee of either house, or any joint committee of the two houses, shall not be used as evidence in any criminal proceedings against such witness in any court of justice: Provided, that no official paper or record produced by such witness on such examination shall be held or taken to be included within the privilege of such evidence so as to protect such witness from any criminal proceeding as aforesaid, and no witness shall hereafter be allowed to refuse to testify to any fact, or to produce any paper touching which he shall be examined by either house, or by any of the committees, for the reason that his testimony touching such fact, or the production of such paper, may tend to disgrace him or render him infamous: Provided, further, that nothing in this act shall be construed to exempt any witness from prosecution and punishment for perjury committed by him in testifying as aforesaid.
25 ILCS 5/6