Section 805 ILCS 215/107 - Supplemental principles of law; rate of interest(a) Unless displaced by particular provisions of this Act, the principles of law and equity supplement this Act. (b) If an obligation to pay interest arises under this Act and the rate is not specified, the rate is that specified in Section 4 of the Interest Act. Added by P.A. 093-0967, § 107, eff. 1/1/2005.