Mich. Comp. Laws § 247.472: Tax set aside; parties to action.

Sec. 72.

In case any suit shall be brought to set aside any tax assessed under the provisions of this act, or in any way attacking the legality of the proceedings had under this act, the county road commissioners, or the state highway commissioner, shall be made a party to such suit. The county in which such road district shall be situated, if operating under the county road system, shall likewise be made a party and process shall be served upon the clerk of such county.