Prescription and Over-the-Counter Drugs and OWI in Michigan

In Michigan, a prescription does not change the legal test for impaired driving. The OWI offense in MCL 257.625(1)(a) and the visibly-impaired offense in MCL 257.625(3) apply to impairment from alcohol, "a controlled substance, or other intoxicating substance," and section 625 contains no exception for a drug taken as prescribed.^[1] What matters is the drug's effect on the person's ability to drive.^[10][11] At the same time, the "any amount" drug offense applies only to Schedule 1 substances and cocaine, so for most prescription medicines the prosecution must prove impairment, not just presence.^[5][12][3]

Which drugs the OWI statute covers

Section 625 uses two drug categories, and between them they reach nearly any medicine that can affect driving.

• Controlled substances. The Vehicle Code borrows the Public Health Code's definition.^[13] That definition covers any drug, substance or immediate precursor in schedules 1 through 5.^[2] Schedule 1 is for substances with a high potential for abuse and no accepted medical use in treatment in the United States.^[12] Schedules 2, 3, 4 and 5 are, by their placement criteria, for substances with a currently accepted medical use in treatment in the United States.^[3]
• Other intoxicating substances. This means a substance other than alcohol or a controlled substance that is recognized as a drug in the U.S. Pharmacopoeia, the Homeopathic Pharmacopoeia of the United States or the National Formulary, or a non-food substance, including vapors or fumes, used in a manner or for a purpose for which it was not intended and that may result in intoxication.^[4]

The "other intoxicating substance" wording was added by 2012 PA 543, effective 31 March 2013; before that, the under-the-influence offense named only alcohol, controlled substances, or a combination.^[14] Older web pages that describe only alcohol and "controlled substances" predate that change.

Presence versus impairment

Three main offenses can apply when a drug is involved, and they turn on different questions.

Offense	What must be shown about the drug
OWI, under the influence (625(1)(a))	The person was under the influence of a controlled substance, another intoxicating substance, alcohol, or a combination[6]
OWVI, visibly impaired (625(3))	The person's ability to operate was visibly impaired because of one of those substances[7]
Any amount (625(8))	Any amount of a Schedule 1 substance or cocaine in the body, whether or not the driver was impaired[5]

Jurors in an under-the-influence case are told that the substance must have substantially lessened the person's ability to operate a vehicle in a normal manner; the person need not be falling down or hardly able to stand up.^[10] For OWVI, they are told the person drove with less ability than an ordinary careful driver, lessened to the point another person would notice, and it is the ability to drive, not the manner of driving, that must be visibly lessened.^[11] OWVI does not require proof of erratic driving; signs observed at the stop can be enough to send the charge to a jury.^[15]

Because schedules 2 through 5 are not part of the "any amount" offense, a positive test for a medicine on those schedules does not by itself establish a section 625(8) violation.^[5][3] The numeric limits in section 625(1) are alcohol-content limits, and the Vehicle Code sets no numeric threshold for THC.^[6][16] Even for Schedule 1, the Supreme Court held that the inactive marijuana metabolite 11-carboxy-THC is not itself a Schedule 1 substance, and in 2021 reversed convictions resting only on an unidentified cocaine metabolite.^[17][18]

How impairment by a drug is proved

The chemical-test provisions do not limit other admissible evidence on whether the person was impaired.^[19] Jurors are told to consider the person's condition at the time of driving, including reflexes, vision, walking and talking, manner of driving and judgment, and whether any abnormality was caused by alcohol or drugs.^[20] Blood and urine tests can show that a drug was present; the details are on blood tests in OWI cases.

Officers trained as drug recognition experts (DREs) are defined in the Vehicle Code as law enforcement officers trained to recognize impairment from a controlled substance rather than, or in addition to, alcohol.^[21] In People v Bowden (2022), a DRE testified that the protocol has 12 steps and covers 7 drug categories; the Court of Appeals reversed an order letting the DRE testify about the degree of marijuana impairment, because the prosecution had not shown the protocol is validated for that purpose.^[22][23] Bowden concerned marijuana; how courts treat DRE opinions about other drugs is decided case by case. See drug recognition experts and evidence in drugged-driving cases.

When an OWI or OWVI charge is based on a controlled substance or other intoxicating substance, the jury must return a special written verdict, or the judge must make a finding on a plea or bench trial, on whether the person was under the influence of or impaired by a drug; no separate verdict is needed when the jury is instructed to decide only the drug-based theory.^[8][9] If the finding is that a drug was involved, the court reports it to the Secretary of State and forwards to the State Police a record of the penalties, which is kept as a public record for at least 7 years.^[9][24]

Blood draws and medical conditions

The implied consent law covers tests of blood, breath or urine after an arrest for an OWI-type offense.^[25] People with hemophilia, diabetes, or a condition requiring a prescribed anticoagulant are not considered to have consented to a blood draw.^[26] Police can still seek a warrant for blood after a refusal.^[27] See Michigan's implied consent law.

Penalties and license effects

A drug-based OWI carries the same criminal penalties as an alcohol OWI, and a 625(8) conviction is sentenced under the same subsection.^[5] A first OWI with a drug carries the same 180-day license suspension as an alcohol OWI.^[28] A first OWVI normally brings a 90-day suspension, but when the visible impairment was caused by a controlled substance, or by alcohol combined with one, the suspension is 180 days.^[29] The penalty details are in first-offense OWI penalties and operating while visibly impaired.

The marijuana exception for registered patients

One narrow protection that resembles a "prescription defense" involves medical marijuana. Marijuana remains on Michigan's Schedule 1 list.^[30] In People v Koon (2013), the Michigan Supreme Court held that the Medical Marihuana Act protects a registered patient who drives with marijuana in his or her system but is not otherwise under the influence, so the "any amount" rule does not apply to a patient who has not lost the act's immunity by failing to act in accordance with it.^[31] The same act does not authorize anyone to drive under the influence of marijuana, and a registered patient can be prosecuted for OWVI.^[32][33] Whether adult recreational users get similar protection is unsettled.^[34] See marijuana and driving.

Practical point: pharmacy labels and package inserts may carry warnings about driving or operating machinery. Reading them, and asking the prescriber or pharmacist how a new medicine or a dose change may affect alertness, is a sensible step before driving.