Mich. Comp. Laws § 691.1609

Sec. 9. (1) If a defendant under this act has a criminal conviction under state or federal law for an act that constitutes participation in illegal marketing of a controlled substance under this act, that person is conclusively presumed to have participated in illegal marketing of a controlled substance for the purposes of this act. (2) If a defendant is proven or presumed to have participated in illegal marketing of a controlled substance, that defendant is presumed to have participated during the 2 years before and the 2 years after the date of the participation or conviction, unless the defendant proves otherwise by clear and convincing evidence. (3) In addition to each county in which a defendant is proven to have actually participated in illegal marketing of a controlled substance, the defendant is presumed to have participated in each county in which the defendant resides, attends school, is employed, or does business during the period of participation. In addition to the counties in which the individual abuser is proven to have obtained or used the controlled substance, the individual abuser is presumed to have obtained or used the controlled substance in each county in which the individual resides, attends school, or is employed during the period of the individual's abuse of that controlled substance, unless the defendant proves otherwise by clear and convincing evidence.