DUI and DWI Overview

What it means to be charged with a DUI (driving under the influence of drugs or alcohol) or DWI (driving while intoxicated).

By , Attorney ● University of San Francisco School of Law
Updated 3/13/2022

Drunk driving is commonly known as "driving under the influence" (DUI) or "driving while intoxicated" (DWI). But states use all kinds of other names: operating under the influence (OUI), driving while visibly impaired (DWVI), operating while impaired (OWI), and so on. Here is some basic information about how DUI offenses are defined and the possible consequences of a DUI.

What "Driving Under the Influence" Means

Each state has its own definition of driving under the influence. These definitions inform drivers of exactly what's illegal and outline what prosecutors must prove to get a DUI conviction in court.

But the DUI laws of all states follow the same basic structure and require proof that the person was operating a vehicle and under the influence. However, these two parts of a DUI charge aren't always as straightforward as they appear.

Operating a Vehicle

The DUI laws of some states—including California—make it illegal to "drive" while under the influence. In other words, to be convicted, the motorist must have actually had the vehicle in motion.

However, the DUI laws of most states—like in Nebraska—not only prohibit driving but also "being in actual physical control" of a vehicle while under the influence. Under this definition, you can get a DUI even if your vehicle never actually moves. The specifics of state laws differ. But the aim of these laws is to allow law enforcement to arrest an impaired motorist who hasn't yet put the car in gear but is in a position to do so.

Under the Influence

All states essentially have two types of DUI laws—impairment and per se laws. In other words, you can be convicted of a DUI:

  • based on being actual impaired by drugs or alcohol, or
  • for being "per se" under the influence based on the concentration of alcohol or drugs in your system.

The level of impairment that qualifies as "under the influence" differs by state. Some states required proof of substantial impairment, while other states require proof of only slight impairment.

Generally, you can get a per se DUI for having a blood alcohol concentration (BAC) of .08% or more (.05% or more in Utah). And a number of states—like Washington—also have per se drug DUI laws.

Per se example: Cindy Heavyweight left work at 5:00 p.m., and—as she had done every day for the past 20 years—drove straight to the bar. As usual, Cindy had six beers and two shots before setting out for home at 8:00 p.m. While driving home, Cindy was stopped by Officer Smith for a broken taillight. Cindy wasn't swerving or driving unsafely. When Officer Smith approached Cindy, he could smell a strong odor of alcohol, but Cindy didn't appear intoxicated. Cindy performed three field sobriety tests perfectly, but a breath test revealed a BAC of.09%. Although Cindy is guilty of driving with a BAC of.08% or higher, she might not be guilty of a DUI based on impairment because there's no evidence that her drinking affected her driving.

The Consequences of a DUI Conviction

Unlike most other driving-related violations, DUIs are generally considered criminal offenses. Most DUIs are misdemeanors, but offenses that involve significant aggravating factors can be felonies.

DUIs tend to carry heavy penalties that typically include license suspension, expensive fines, and possible jail time. It's also becoming more common for state DUI laws to require convicted motorists to use ignition interlock devices (IIDs) for a period of time following license reinstatement.

Talk to a Lawyer

Anyone accused of driving under the influence should contact a lawyer with experience in this area of law. Even if you don't hire a lawyer to represent you, a consultation can be tremendously helpful. A knowledgeable local lawyer should be able to advise you of the law in your state, the local prosecuting office's plea bargaining tendencies, and the implications for your driver's license. A lawyer can also explore potential defenses.

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