Effective June 1, 2014, the Illinois Religious Freedom and Marriage Fairness Act legally recognizes marriage between two persons, regardless of gender (750 IL Comp. Stat. Sec. 5/201 et seq.).
Reciprocity. Except for a common-law marriage, any marriage legally entered into in another jurisdiction is recognized as a marriage under state law.
Conversion of civil union to marriage. A couple in a civil union may apply for and receive a marriage license and have their marriage registered, provided the couple is otherwise eligible to marry under state law.
For a period of 1 year from June 1, 2014, a civil union couple could apply for a marriage certificate without payment of any fee. By signing and returning the certificate to the county clerk, the civil union was converted into a marriage. The effective date of the marriage is the date the couple entered into their civil union.
The U.S. Supreme Court subsequently issued a decision legalizing same-sex marriage in all states and requiring all states to recognize same-sex marriages legally performed in other jurisdictions (Obergefell v. Hodges, 135 S.Ct. 2584 (2015)).