Illinois CERTIFICATE OF DISSOLUTION OF MARRIAGE/CIVIL UNION INVALIDITY OR LEGAL SEPARATION is a document issued by the State of Illinois to either declare an existing marriage or civil union null and void, or to legally separate two parties who are already married or in a civil union. This document is often necessary to dissolve a marriage or civil union in order for the parties to move on with their lives. There are two types of certificates available in Illinois — Certificate of Dissolution of Marriage and Certificate of Dissolution of Civil Union. The Certificate of Dissolution of Marriage is issued when two parties are married and wish to end their marriage. This document is required to obtain a divorce in Illinois. It formally declares the marriage null and void, and it also provides information about the terms of the divorce, such as division of property, spousal support, and child custody. The Certificate of Dissolution of Civil Union is issued when two parties are in a civil union and wish to end their union. This document is required to obtain a legal separation in Illinois. It formally declares the civil union null and void, and it also provides information about the terms of the separation, such as division of property, spousal support, and child custody. Both certificates are issued by the State of Illinois and are required to legally dissolve a marriage or civil union.