Mich. Comp. Laws § 483.5: Common carrier defined; carrier without discrimination.

Sec. 5.

A person engaged in the business of carrying or transporting crude oil or petroleum, or any of the products thereof, or carbon dioxide substances, for hire or compensation or otherwise, by pipe line or lines, within this state, is a common carrier thereof as at common law. Such a common carrier shall not allow or commit any unjust or unlawful discrimination, directly or indirectly, in favor of the carriage, transportation, storage, or delivery of any crude, stock, or storage oil, or petroleum, or any products thereof, or carbon dioxide substances that are in its possession or control, or in which the common carrier is interested, directly or indirectly.