750 ILCS 5/305
Any person, having gone through a marriage ceremony, who has cohabited with another to whom he is not legally married in the good faith belief that he was married to that person is a putative spouse until knowledge of the fact that he is not legally married terminates his status and prevents acquisition of further rights. A putative spouse acquires the rights conferred upon a legal spouse, including the right to maintenance following termination of his status, whether or not the marriage is prohibited, under Section 212, or declared invalid, under Section 301. If there is a legal spouse or other putative spouse, rights acquired by a putative spouse do not supersede the rights of the legal spouse or those acquired by other putative spouses, but the court shall apportion property, maintenance and support rights among the claimants as appropriate in the circumstances and in the interests of justice. This Section shall not apply to common law marriages contracted in the State after June 30, 1905.
750 ILCS 5/305