(735 ILCS 5/8-1501) (from Ch. 110, par. 8-1501)
    Sec. 8-1501. Comparison. In all courts of this State it shall be lawful to prove handwriting by comparison made by the witness or jury with writings properly in the files of records of the case, admitted in evidence or treated as genuine or admitted to be genuine, by the party against whom the evidence is offered, or proved to be genuine to the satisfaction of the court.
(Source: P.A. 82-280.)