405 ILCS 5/1-110.5 : Health and Safety — Mental Health — Mental Health and Developmental Disabilities Code — Chapter I. Short Title and Definitions —110.5 TEXT PDF "Substitute decision maker" means a person who possesses the authority to make decisions under the Powers of Attorney for Health Care Law or under the Mental Health Treatment Preference Declaration Act. 405 ILCS 5/1-110.5 P.A. 91-726, eff. 6/2/2000.