The American Civil Liberties Union says it's filing a lawsuit to enforce the legal rights of about 300 same-sex couples who were married during a one-day window between separate federal court decisions.
Detroit U.S. District Judge Bernard Friedman ruled March 21 that Michigan's ban on same-sex marriage is unconstitutional. Clerks in four counties held unscheduled Saturday openings the next day, issuing about 300 marriage licenses.
The 6th Circuit Court of Appeals in Cincinnati stayed the ruling a few hours later.
Gov. Rick Snyder says Michigan government agencies aren't yet recognizing the new same-sex marriages in such areas as adoption and child custody.
ACLU spokeswoman Rana Elmir says the group is suing to require state recognition of the marriages. She says it's announcing details at a Monday afternoon Detroit news conference.