Compiled Laws, Chapter 750. Michigan Penal Code § 750.60

Sec. 60.(1) A person who cuts the bone of the tail of a horse for the purpose of docking the tail, or who causes or knowingly permits the cutting to be done upon the premises of which he or she is the owner, lessee, proprietor, or user, or who assists in or is present at such cutting, is guilty of a misdemeanor punishable by imprisonment for not more than 1 year or a fine of not more than $1,000.00.However, this subsection does not apply to the cutting of the bone of the tail of a horse for the purpose of docking the tail when a certificate of a regularly qualified veterinary surgeon is first obtained certifying that the cutting is necessary for the health or safety of the horse.

(2) If a horse is found with its tail cut and with the wound resulting from the cutting unhealed, upon the premises of any person, those facts shall be prima facie evidence that the person occupying or using the premises on which that horse is found has committed the offense described in subsection (1).

(3) If a horse is found with its tail cut and with the wound resulting therefrom unhealed, in the charge or custody of any person, that fact shall be prima facie evidence that the person having the charge or custody of that horse has committed the offense charged in subsection (1).