Mich. Comp. Laws § 339.1811

Sec. 1811. (1) The purchase of a vault or similar receptacle designed or intended to enclose or receive a casket, coffin, or other similar container from a particular individual, partnership, association, or corporation shall not be required as a condition to burial in a cemetery in this state. There shall not be a discrimination by price, burial fee, or otherwise by reason of a failure to purchase the vault or similar receptacle from or under the direction of the cemetery or the owner of the cemetery. (2) This section shall not limit the right of a cemetery to require the use of a vault in a burial in the cemetery.