Per-se DUI: test-result grounds and impairment grounds

An impairment ground describes the person's condition rather than a measured number. Nebraska's statute makes it unlawful to operate or be in the actual physical control of any motor vehicle "while under the influence of alcoholic liquor or of any drug." Arkansas's statute, A.C.A. § 5-65-103, makes it unlawful for a person "who is intoxicated" to operate or be in actual physical control of a motorboat on the waters of the state or a motor vehicle.

Virginia's statute, Va. Code § 18.2-266, contains several impairment clauses. Clause (ii) covers driving or operating a motor vehicle, engine or train while under the influence of alcohol. Clauses (iii) and (iv) cover narcotic drugs, other self-administered intoxicants or drugs, and the combined influence of alcohol and drugs, in each case "to a degree which impairs his ability to drive or operate any motor vehicle, engine or train safely." Virginia's statute provides that "motor vehicle" includes mopeds while operated on the public highways of the Commonwealth.

Montana's statute, Mont. Code Ann. § 61-8-1002, covers driving or being in actual physical control of a vehicle or commercial motor vehicle upon the ways of the state open to the public "while under the influence of alcohol, any drug, or a combination of alcohol and any drug."

A per-se ground is defined by a measured concentration. Nebraska's statute lists its concentration grounds as alternatives to its impairment ground. Arkansas's statute makes it unlawful to operate or be in actual physical control of a motorboat on the waters of the state or a motor vehicle "if at that time the alcohol concentration in the person's breath or blood was" at or above the figure it sets, based on a definition of alcohol concentration found in another section of Arkansas's code.

Missouri's statute, Mo. Rev. Stat. § 577.012, frames its concentration ground as a distinct offense: "A person commits the offense of driving with excessive blood alcohol content if such person operates" a vehicle, or a commercial motor vehicle, at or above the concentration the statute sets for each.

Montana's statute includes a concentration ground for a noncommercial vehicle upon the ways of the state open to the public, measured "as shown by analysis of the person's blood, breath, oral fluid, or other bodily substance."

Arkansas's statute states that "An alcohol-related offense under this section is a strict liability offense." Montana's statute provides that absolute liability, as provided in a cross-referenced section, is imposed for a violation of its section.

Nebraska's statute states blood and breath as separate alternatives: one ground refers to a concentration of alcohol in a person's blood, and another to a concentration of alcohol in the person's breath, each measured as the statute specifies.

Missouri's statute provides that percent by weight of alcohol in the blood is based on a measure of blood or breath and "may be shown by chemical analysis of the person's blood, breath, saliva or urine." It adds that the test is to be conducted in accordance with testing provisions it cross-references.

Virginia's clause (i) refers to a blood alcohol concentration or a breath measure at or above the figures it sets, "as indicated by a chemical test administered as provided in this article." Arkansas's concentration ground refers to the alcohol concentration in the person's breath or blood.

Missouri's statute sets out a separate alternative for a person who operates "A commercial motor vehicle while having" a stated concentration of alcohol in the blood, alongside its alternative for operating a vehicle.

Montana's statute includes a separate ground for "a commercial motor vehicle within this state while the person's alcohol concentration," as shown by analysis of blood, breath, oral fluid or other bodily substance, is at or above the figure it sets. Montana's commercial ground refers to a vehicle "within this state," while its noncommercial concentration ground refers to the ways of the state open to the public. The figures for each are set in the statutes and are not stated here.

Virginia's clause (v) makes it unlawful to drive or operate a motor vehicle, engine or train "while such person has a blood concentration of any of the following substances at a level that is equal to or greater than" levels the statute lists for cocaine, methamphetamine, phencyclidine and a further named substance.

Montana's statute contains a ground for a noncommercial vehicle or commercial motor vehicle within the state while the person's tetrahydrocannabinol level, "excluding inactive metabolites," as shown by analysis of the person's blood or other bodily substance, is at or above a stated level.

A separate Montana ground covers a noncommercial vehicle or commercial motor vehicle on the ways of the state open to the public while, "without a valid prescription, the person has an amount of any of the following prohibited substances in their body," as shown by blood analysis, at or above the amounts in a table. The table lists amphetamine, cocaine, a cocaine metabolite, heroin, heroin metabolites, lysergic acid diethylamide, methamphetamine, phencyclidine and fentanyl. The valid-prescription condition appears in that table ground.

Montana's statute attaches inferences to a test result in the trial of any civil or criminal action or proceeding arising out of acts alleged to have been committed by a person driving or in actual physical control of a vehicle while under the influence of alcohol. The result must come from a sample of blood, breath, oral fluid or other bodily substance "drawn or taken within a reasonable time after the alleged act."

The statute describes three ranges. In the lowest, it may be inferred that the person was not under the influence of alcohol. In a middle range, the result "may not give rise to any inference that the person was or was not under the influence of alcohol," but it may be considered with other competent evidence in determining guilt or innocence. In the highest, it may be inferred that the person was under the influence of alcohol, and "The inference is rebuttable."

Montana's statute also provides that these inferences do not limit the introduction of any other competent evidence bearing on whether the person was under the influence of alcohol, drugs, or a combination of alcohol and drugs.

Deadlines, limits and penalty ranges are set by each state’s statutes, so this page does not state them. Each state page shows them with the official source and the date they were verified — or says plainly that a figure has not been confirmed yet.