Cohabitation Agreements in Illinois

Cohabitation agreements are private contracts between unmarried parties who live together which outline the parties' rights surrounding their shared property. They can be viewed as comparable to prenuptial agreements, but between unmarried partners. These agreements are generally unenforceable in Illinois for violating public policy. However, the Illinois Supreme Court in Blumenthal v. Brewer noted that unmarried cohabitants may bring common-law claims, such as those for constructive trusts or restitution, so long as the claims aren’t based on the cohabitation or relationship itself and instead has independent legal grounds. Blumenthal v. Brewer, 69 N.E.3rd 834 (Ill. 2016).

The court initially examined this issue in Hewitt v. Hewitt, 77 Ill.2d 49 (1979). Here, the court was asked to determine whether unmarried cohabitants were entitled to equal shares of the property accumulated during their relationship. The couple in this case originally believed that they were married under common law in Iowa after the plaintiff fell pregnant, at which point the defendant pledged he would “share his life, his future, his earnings, and his property” with her. After fifteen years of holding themselves out as husband and wife and having three children together, the plaintiff filed for divorce. The plaintiff asked the court for half of the property and profits accrued during their cohabitation. The trial court initially dismissed her claim, but an appellate court disagreed. That court was heavily influenced by Marvin v. Marvin, 18 Cal. 3rd 660 (1976), in which the California Supreme Court held that cohabitation agreements were enforceable under theories of contract law unless the consideration was explicitly based on sexual favors. On review, the Illinois Supreme Court held cohabitation agreements to be illegal in general, regardless of consideration. The court held that these agreements were, in effect, acting as common law marriages, which have been prohibited in Illinois since 1905. Further, they viewed the issue as one better suited for the legislature to determine than the judiciary, as it concerns complex public policy issues.

The most determinative case the Illinois Supreme Court has heard on this issue in recent years is Blumenthal v. Brewer. Blumenthal v. Brewer, 69 N.E.3rd 849, 860. This case concerned a same-sex couple who had lived together unmarried with children from 1981-2010. The plaintiff filed for partition of their jointly owned residence, which alone did not concern the parties’ relationship as unmarried cohabitants. However, the defendant’s counterclaim seeking common law remedies did concern that relationship, and the Illinois Supreme Court was asked to review their decision in Hewitt v. Hewitt. The defendant claimed that neither Illinois law nor society at large treats unmarried couples who reside together negatively, and therefore the public policy rationale in Hewitt is outdated and must be overturned. The court acknowledged the changes in marriage law since Hewitt was decided, such as the adoption of no-fault divorce and the equal treatment of marital and non-marital children. Despite the many changes in Illinois marriage law, common law marriage remains prohibited. As the determining factor in the Hewitt decision was that cohabitation agreements would be acting as common law marriages, the court upheld the decision, and cohabitation agreements remain unenforceable today. In conclusion, unmarried cohabitants in Illinois may form enforceable private agreements, but couples residing together do not develop property rights absent an explicit agreement.