Illinois Marriage Dissolution Act On Child Custody

A court of this State competent to decide child custody matters has jurisdiction to make a child custody determination in original or modification proceedings as provided in Section 201 of the Uniform Child-Custody Jurisdiction and Enforcement Act as adopted by this State. (b) A child custody proceeding is commenced in the court: 

(1) by a parent, by filing a petition:  (i) for dissolution of marriage or legal separation or declaration of invalidity of marriage; or (ii) for custody of the child, in the county in which he is permanently resident or found by a person other than a parent, by filing a petition for custody of the child in the county in which he is permanently resident or found, but only if he is not in the physical custody of one of his parents; or by a stepparent, by filing a petition, if all of  the following circumstances are met: 

The child is at least 12 years old; the custodial parent and stepparent were married for at least 5 years during which the child resided with the parent and stepparent; the custodial parent is deceased or is disabled and cannot perform the duties of a parent to the child; the stepparent provided for the care, control, and welfare to the child prior to the initiation of custody proceedings the child wishes to live with the stepparent; and it is alleged to be in the best interests  and welfare of the child to live with the stepparent as provided in Section 602 of this Act.