A civil union is a legally recognized relationship between members of a same-sex couple, with rights similar to those of a marriage relationship.
As of my knowledge cutoff in early 2023, Michigan does not have a legal status specifically called 'civil union.' However, same-sex marriage has been legal in Michigan since the U.S. Supreme Court's decision in Obergefell v. Hodges on June 26, 2015, which legalized same-sex marriage nationwide. This ruling means that same-sex couples in Michigan can marry, and they have the same legal rights and responsibilities as opposite-sex couples in marriage. Prior to this decision, Michigan had a constitutional amendment banning same-sex marriage, which is no longer enforceable. Therefore, in Michigan, same-sex couples looking for legal recognition of their relationship would pursue marriage rather than a civil union.