An Illinois Supreme Court ruling is a step backward for same-sex couples and will harm all unmarried domestic partners who might want a court to decide a property dispute after a break-up, according to gay rights advocates.

The court on Thursday rejected 5-2 a claim by a Chicago woman who split up with her partner after nearly 30 years of living together and raising children. The two women split in 2008, years before Illinois legalized same-sex marriage.

Eileen Brewer, a Cook County judge, was seeking a share in Dr. Jane Blumenthal’s medical practice as restitution. Her attorneys asked the state high court to overturn its 1979 position barring such claims by unmarried partners.

The case was seen by some legal observers as a chance for the justices to update their position in the context of expanding protections for same-sex couples and all unmarried couples and their children.

Writing for the majority , Justice Lloyd Karmeier rejected the argument, saying the 1979 ruling in Hewitt v. Hewitt “remains good law” and if the Legislature had wanted to revive common-law marriage, it would have done so. Common-law marriage has been barred in Illinois for more than a century.

In her dissent, Justice Mary Jane Theis wrote that Illinois, Georgia and Louisiana are the only states that don’t recognize property-division claims between unmarried partners. She said the majority opinion reaffirmed “an oddly myopic and moralistic view of cohabitation.”

Brewer’s attorneys may ask the U.S. Supreme Court to review the case, said Shannon Minter, legal director of the San Francisco-based National Center for Lesbian Rights, which assisted Chicago attorney Angelika Keuhn on Brewer’s behalf.

“This is completely out of step with other states and the realities of families today,” Minter said.

“Families deserve protections and the help of the courts when relationships end, whether the couples were married or not,” said Susan Sommer of the gay rights group Lambda Legal. “And when access to marriage was unconstitutionally barred to same-sex families, it is the height of injustice to give legal protections solely to those who married.”

Blumenthal’s attorney, Reuben Bernick, said the ruling should not be seen as a setback for gay rights. The couple could have gotten married in another state, the Chicago attorney said, and in fact they had obtained a Massachusetts marriage license, but never used it.

As for unmarried couples in Illinois, Bernick said: “If they want to take advantage of the provisions available only in divorce, yes, they should get married. If they don’t care about that, then nobody’s making them get married.”

Read the full opinion here.

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