What "Under the Influence" Means in a Michigan OWI Case

In Michigan, a driver is "under the influence" when alcohol, drugs or another intoxicating substance substantially lessened the driver's ability to operate a vehicle in a normal manner.^[1] It is one of three ways to prove operating while intoxicated, and it does not depend on a breath or blood number: a case can go forward on observed impairment alone.^[2][3]

What the statute says

MCL 257.625(1) defines "operating while intoxicated" to include the situation where "the person is under the influence of alcoholic liquor, a controlled substance, or other intoxicating substance or a combination" of them.^[2] Section 625 does not itself define "under the influence"; the definition jurors receive comes from the model jury instructions, discussed below.^[7]

The substances covered are broad:

• Alcoholic liquor.^[2]
• A controlled substance, which the Vehicle Code defines by reference to the Public Health Code's definition in MCL 333.7104, including controlled substance analogues.^[8]
• Another intoxicating substance: a substance other than alcohol or a controlled substance that is recognized as a drug in the U.S. Pharmacopoeia, Homeopathic Pharmacopoeia or National Formulary, or a non-food substance, including vapors or fumes, used in a way it was not intended and that may cause intoxication.^[9]
• A combination of any of these.^[2]

The "other intoxicating substance" language took effect March 31, 2013; before that, the statute covered only alcohol, controlled substances, or a combination of the two.^[10] The guides on drugged driving and prescription and over-the-counter drugs cover the drug side.

The jury-instruction test

Michigan's model criminal jury instruction for OWI, M Crim JI 15.2, tells jurors that under the influence means that, because of the substance, "the defendant's ability to operate a motor vehicle in a normal manner was substantially lessened."^[1] It adds two balancing statements:^[1]

• A person "does not have to be falling down or hardly able to stand up" to be under the influence.^[1]
• Having drunk alcohol, or smelling of it, "does not prove, by itself, that the person is under the influence."^[1]

The instruction then states the test: whether, because of the substance, the defendant's mental or physical condition was significantly affected and the defendant was no longer able to operate a vehicle in a normal manner.^[1] The prosecutor must prove this element, like every element, beyond a reasonable doubt.^[1]

The jury instructions were renumbered in February 2021. M Crim JI 15.2 is now the OWI instruction; older sources that call it 15.1 or 15.3 are using the earlier numbering.^[11]

What evidence bears on impairment

The instructions also list what jurors should consider. Under M Crim JI 15.5(1), they look at the defendant's mental and physical condition at the time of driving, including reflexes, ability to see, way of walking and talking, manner of driving and judgment, and whether any abnormality was caused by alcohol or drugs.^[12] Evidence offered on these questions can include:

• The officer's observations of driving, speech, walking and judgment.^[12]
• Standardized field sobriety tests. A person qualified by training or experience may testify about them on a proper foundation, and non-standardized tests may be admitted if they comply with the rules of evidence.^[13] NHTSA's own manual describes these tests as a tool for seeing visible signs of impairment and "not a pass/fail test."^[14]
• Chemical test results, if any. Jurors are told to consider whether a test was technically accurate, whether the equipment was maintained, whether it was given correctly and whether the person giving it was trained.^[15]

The chemical-testing provisions expressly do not limit "any other admissible evidence" on whether the person was impaired or had an unlawful alcohol content.^[4] See the evidence in an OWI case and field sobriety tests.

The per se alternative: 0.08 and 0.17

The other two ways to prove intoxication are numbers: an alcohol content of 0.08 grams or more, or 0.17 grams or more, per 100 milliliters of blood, 210 liters of breath or 67 milliliters of urine.^[2] On those theories, the jury may convict "whether or not this alcohol content affected" the defendant's ability to drive.^[16] Lawyers call this a "per se" offense: the number is the violation.

A chemical test result is presumed by statute to be the same as the person's level at the time of driving, and the jury instruction tells jurors they "may infer" that and may give the test whatever weight it deserves.^[17][18] Where there is evidence that the person drank after driving but before the test, jurors may consider it.^[18] The guide to the time-of-driving question covers this.

Why a case can go forward without a number

The Court of Appeals describes the third OWI element as "disjunctive": the prosecution may prove either that the defendant was under the influence or that the defendant had an unlawful alcohol content.^[3] So a case may be charged and tried on impairment alone when there is no test result, when a result is below 0.08, or when the case involves marijuana, for which the Vehicle Code sets no numeric THC limit.^[3][19]

A missing test is not always a missing test, though. After a refusal, police may seek a court order for a chemical test.^[20] At trial, evidence of a refusal is admissible only to show that a test was offered, not as evidence of guilt, and the jury must be so instructed.^[21] See refusal evidence at trial.

Under the influence compared with visibly impaired

Operating while visibly impaired (OWVI), under MCL 257.625(3), is a separate offense with its own standard.^[22] The jury is told that OWVI means the defendant drove with less ability than an ordinary careful driver, lessened to the point that another person would notice, and that it is the ability to drive, not the manner of driving, that must be visibly lessened.^[6] On an OWI charge, the judge or jury may return a verdict of OWVI instead, and the OWI jury instruction allows OWVI to be given as a lesser offense.^[22][5] The OWVI guide explains the differences in penalties and license sanctions.

Common misunderstandings

• "Under 0.08 means I was legal." A reading under 0.08 rules out only the 0.08 and 0.17 theories. The under-the-influence and OWVI theories remain.^[2][22]
• "The officer smelled alcohol, so that proves it." The jury instruction says the smell of alcohol or having had a drink does not prove, by itself, that a person was under the influence.^[1]
• "Under the influence means falling-down drunk." The same instruction says a person does not have to be falling down or hardly able to stand.^[1]
• "Under 21 works the same way." Drivers under 21 face a separate offense for any bodily alcohol content: 0.02 up to under 0.08, or any alcohol from drinking other than as part of a religious service or ceremony. See the zero-tolerance guide.^[23]