Mich. Comp. Laws § 247.444
The board of review shall proceed to hear the proofs and allegations of the county, or of any city assessed at large, and of the several townships at large, in respect to the matter of the appeal, and shall proceed to view the lands benefited by such improvement, and to review the total per cent ordered to be paid by the county at large, and by each township, including the sum total per cent assessed upon lands benefited in such township, and if, in their judgment, there be manifest error or inequality in such assessment, they shall order, or make such changes therein within the limitations hereinbefore provided, as they may deem just and equitable. The board of review shall not equalize the assessment between the several tracts or parcels of land. Should the board of review find, upon personal examination, that there are lands liable to be assessed for the construction of such improvement, that were not included in the assessment district made by the county road commissioners, or the state highway commissioner, they shall add such lands to the assessment district for such improvement. Before adding any lands to such special assessment district not included in the final order of the county road commissioners, or the state highway commissioner, the said board of review shall give the same notice as hereinbefore provided to be given by the county road commissioners, or the state highway commissioner, in establishing a special assessment district. The board of review shall meet at the time and place mentioned in their notice, to hear objections from the persons interested with respect to change in such district. On hearing such objections, the board of review, should they still deem it just and equitable that additional lands be included in the district, shall make their order in accordance therewith. The action and decision of the board of review shall be final. The action and decision of such board shall be reduced to writing and signed by a majority making the same, and shall be delivered to the county road commissioners, or the state highway commissioner, together with all other papers relating thereto.
MCL 247.444