Mich. Comp. Laws § 123.503: Allotment of work by public officers.

Sec. 3.

It is further provided that when, in the judgment of such officer, board, commission, committee or department, the volume of work regularly advertised for construction would justify such course, bidders on public work may be rated according to their experience, equipment and resources and be furnished with proposals, plans and specifications for only such type and quantity of work as their qualifications as outlined in section 1 of this act would warrant.