Public universities and governments can't provide health insurance to the partners of gay employees without violating the state constitution, the Michigan Court of Appeals ruled Friday.
A three-judge panel said a 2004 voter-approved ban on gay marriage also applies to same-sex domestic partner benefits.
"The marriage amendment's plain language prohibits public employers from recognizing same-sex unions for any purpose," the court said.
The decision reverses a 2005 ruling from an Ingham County judge who said universities and governments could provide the benefits.
A constitutional amendment passed by Michigan voters in November 2004 made the union between a man and a woman the only agreement recognized as a marriage "or similar union for any purpose." Those six words led to a fight over benefits for gay couples.
Gay couples and others had argued that the public intended to ban gay marriage but not block benefits for domestic partners.
But the court said: "It is a cornerstone of a democratic form of government to assume that a free people act rationally in the exercise of power, are presumed to know what they want, and to have understood the proposition submitted to them in all of its implications, and by their approval vote to have determined that the proposal is for the public good and expresses the free opinion of a sovereign people."
The case likely will be appealed to the Michigan Supreme Court. Twenty-one gay couples who work for the city of Kalamazoo, universities and the state filed the lawsuit.