Michigan is appealing the decision to strike down a law which denies domestic partner benefits to gay couples.
The law, passed in 2011, bans schools and local governments from offering health insurance or any benefits to same-sex partners of employees.
According to Associated Press, it was overturned by District Judge David Lawson last summer, but the state’s appeal will be heard on Tuesday.
Michael Steinberg, legal director at the Michigan branch of the American Civil Liberties Union, said: “I can’t think of a more mean-spirited piece of legislation, yet the attorney general continues to fight for the state’s ability to discriminate.
“It’s very troubling.”
ACLU attorney John Knight, representing five same-sex couples in the case, said the law amounts to state control over the lives of local officials.
He also said the cost of health insurance for domestic partners is only a ‘tiny fraction’ of what public employers spend on overall coverage, and would not amount to a large increase in spending.
The state is currently embroiled in a separate legal battle over same-sex marriage, after a ban was struck down last month, but put back into place pending appeal after couples had already begun to marry.