Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.2955a

(a) “Controlled substance” means that term as defined in section 7104 of the public health code, Act No. 368 of the Public Acts of 1978, being section 333.7104 of the Michigan Compiled Laws.

(b) “Impaired ability to function due to the influence of intoxicating liquor or a controlled substance” means that, as a result of an individual drinking, ingesting, smoking, or otherwise consuming intoxicating liquor or a controlled substance, the individual's senses are impaired to the point that the ability to react is diminished from what it would be had the individual not consumed liquor or a controlled substance. An individual is presumed under this section to have an impaired ability to function due to the influence of intoxicating liquor or a controlled substance if, under a standard prescribed by section 625a of the Michigan vehicle code, Act No. 300 of the Public Acts of 1949, being section 257.625a of the Michigan Compiled Laws, a presumption would arise that the individual's ability to operate a vehicle was impaired.