Mich. Comp. Laws § 550.927

Sec. 27. A contract between a carrier or third party administrator that is a pharmacy benefit manager and a pharmacy must not prohibit the pharmacy from disclosing the current selling price of a drug in accordance with section 17757 of the public health code, 1978 PA 368, MCL 333.17757. This section applies to a contract described in this section executed, extended, or renewed on or after the effective date of the amendatory act that added this section.