The Illinois Religious Freedom Protection and Civil Union Act gives couples in a civil union the same rights, benefits, and legal responsibilities as married couples (750 IL Comp. Stat. Sec. 75/1). A "civil union" under the act is defined as the legal relationship between two persons, of either the same or opposite sex.
A civil union is prohibited if it is:
• Entered into before both parties attain 18 years of age
• Entered into before the dissolution of a marriage or civil union or substantially similar legal relationship of one of the parties
• Between an ancestor and a descendent or between siblings, whether the relationship is by the half or the whole blood or by adoption
• Between an aunt or uncle and a niece or nephew, whether the relationship is by the half or the whole blood or by adoption
• Between first cousins