Mich. Comp. Laws § 750.310
This chapter shall not be construed to prohibit or make unlawful the operation of a game of skill or chance pursuant to the Michigan Exposition and Fairgrounds Act or the giving or payment of purses, prizes, or premiums to players in a game or participants in a contest or to the owner, driver, manager, or trainer of animals or the drivers, mechanics, or operators of a machine or the giving or payment of entry fees or the payment of expenses or reward for services or labor in connection with a race, contest, or game but it shall apply to the selling of pools or to a transaction whereby money or a valuable thing shall be paid as a gain or speculation on the result of a contest, race, game, or event not known to the parties to be certain and concerning which the parties to the transaction do not render service directly related to the holding of the contest, race, or game or the bringing about of the event.
MCL 750.310