Amends the Illinois Marriage and Dissolution of Marriage Act. Requires the form for an application for a marriage license to include whether either party is under a court-ordered guardianship in any State in the United States. Provides that a county clerk shall issue a license to marry and a marriage certificate form, among other requirements, upon being furnished satisfactory proof that neither party to the marriage is under a court-ordered guardianship, or that if at least one party is under a court-ordered guardianship, there has been a judicial determination that the marriage is in the best interests of the person or persons under court-ordered guardianship. Amends the Guardians For Adults With Disabilities Article of the Probate Act of 1975. Requires the court, when determining whether a marriage is in the best interests of a ward, to follow (rather than consider) specified standards. Provides that if a best interests hearing is not held before a judicial officer prior to a ward entering into marriage, then the marriage is without legal effect and void ab initio. Provides that any person who knowingly enters a marriage with a ward without following the required procedures shall be guilty of a Class 4 felony.