Mich. Comp. Laws § 247.471

Sec. 71. Any taxes that may have been assessed and returned delinquent to the county treasurer upon any lands and by virtue of the provisions of this act and remaining unpaid, may be sued for, by the county road commissioners of the county in which such delinquent lands are situated, or by the state highway commissioner, in an action of assumpsit before any court of competent jurisdiction; or the county road commissioners, or the state highway commissioner, may file their bill in equity to enforce the lien of such tax against the real estate charged therewith, in the same manner as mortgages are foreclosed in chancery. The court may order the sale of such delinquent lands at any time after 6 months from the filing of such bill in chancery.