Mich. Comp. Laws § 460.833a: Records, books, documents, and papers; exclusion from public disclosure; exception.

Sec. 33a.

(1) Records, books, documents, and papers of a joint agency or a municipal electric utility system, including those maintained electronically, may be exempted from public disclosure by the board of commissioners of the joint agency or the governing body of the municipal electric utility system if any of the following apply:

(a) They contain specific pricing or other confidential or proprietary information.

(b) They pertain to the development, construction, financing, or leasing of a project.

(c) They contain information which was received from a power utility or other person and which is subject to a confidentiality agreement.

(2) Upon a showing of good cause, disclosure subject to appropriate confidentiality provisions may be ordered by a court.