750 ILCS 75/60: Respect for marriages and civil unions entered into in other jurisdictions.

A civil union, or a substantially similar legal relationship other than common law marriage, legally entered into in another jurisdiction, shall be recognized in Illinois as a civil union. A marriage, whether of the same sex or different sexes and providing that it is not a common law marriage, legally entered into in another jurisdiction, shall be recognized in this State as a marriage in accordance with the provisions of the Illinois Marriage and Dissolution of Marriage Act, except that Section 216 of the Illinois Marriage and Dissolution of Marriage Act shall not apply to marriages of same-sex couples validly entered into in another jurisdiction.