(A) A person is justified in the use of force against when and to the extent that he or she reasonably believes that the conduct is necessary to prevent or terminate such other’s trespass on or other tortuous or criminal interference with either real property, other than a dwelling, or personal property, lawfully in his or her possession or in the possession of another who is a member of his or her immediate family or household or of a person whose property he or she has a legal duty to protect. However, he or she is justified in the use of force which is intended or likely to cause death or great bodily harm only if he or she reasonably believes that the force is necessary to prevent the commission of a forcible felony.
(B) In no case shall any act involving the use of force justified under this section give rise to any claim or liability brought by or on behalf of any person acting within the definition of "aggressor" set forth in ILCS Chapter 720, Act 5, § 7-4, or the estate, spouse, or other family member of such a person, against the person or estate of the person using such justified force, unless the use of force involves willful or wanton misconduct.
(ILCS Chapter 720, Act 5, § 7-3) (1981 Code, § 42.07, 7-3)