Criminal Law

DUI, DWI, OUI: Definitions and Terminology for Driving Under the Influence

By Richard Stim, Attorney
DUI case legal lingo explained.

DUI lawyers, police, and legislators have developed their own terminology and shorthand when it comes to driving under the drunk and drugged driving cases. Below are some of the common terms explained.

Reasonable Suspicion and Probable Cause

Reasonable suspicion. Reasonable suspicion is a general criminal law concept that also applies to driving under the influence case. It requires that officers have an objectively reasonable basis for suspecting criminal activity before detaining someone. It’s a standard that’s lower than probable cause (discussed below). Before pulling someone over, an officer needs only a reasonable suspicion that the motorist has violated the law. An officer can pull you over, for example, after witnessing you swerve across the road, drift in and out of a lane, or commit some other traffic violation.

Probable cause. Probable cause is another standard that applies to all kinds of criminal cases: It’s the measure by which judges evaluate arrests. There’s probable cause for an arrest if the facts support an objective belief that the suspect has committed a crime. So, after pulling you over, but before arresting you for DUI, a police officer must have probable cause to believe that you were too impaired to drive.

Why reasonable suspicions and probable cause matter. Traffic stops and DUI arrests that aren't supported by reasonable suspicion and probable cause, respectively, are illegal. An illegal stop or arrest could result in crucial evidence and the charges being thrown out.

Field Sobriety Tests

Police officers use a set of preliminary tests known as field sobriety tests (FSTs) to determine if a DUI suspect is intoxicated. These physical tests—as distinguished from chemical blood and breath testing—assess the driver’s physical dexterity and ability to follow directions. The most common FSTs are:

  • standing on one leg
  • walking and turning
  • counting backwards
  • reciting the alphabet
  • placing finger-to-nose, and
  • Horizontal Gaze Nystagmus (HGN), a test in which the suspect follows the officer's moving finger.
A driver generally isn't required to participate in FSTS. But poor FST performance can certainly lead to a DUI arrest.

Chemical Test

If field sobriety tests don’t eliminate the likelihood of intoxication, police officers generally ask the driver to provide a breath sample using a portable breathalyzer called a "preliminary alcohol screening" (PAS) device. And after a DUI, police typically request that the suspect take a more accurate breath test (an "evidential breath test") or submit to blood sampling. A third, less favored chemical test involves urine analysis (discussed below). All three tests are administered to determine the suspect’s blood alcohol concentration (BAC).


BAC refers to the proportion of alcohol found in a driver’s blood. BAC—measured as weight per unit of volume—is reported as a percentage of one percent of the driver's blood. For example, a BAC of.20%, means that 20/100 (or 1/5) of one percent of the driver's blood is comprised of alcohol. Typically, the level at which a driver is deemed too intoxicated to drive is .08%.

In all states, it’s illegal to drive with a BAC of .08% or more (underage drivers are subject to lower limits)—called DUI per se—regardless of whether your ability to drive safely was actually impaired.


The law prohibiting drunk driving is known in most states by the acronym DUI (for driving under the influence). But many states use other acronyms, including:

  • DUIL (driving under the influence of liquor)
  • DWI (driving while intoxicated)
  • OMVI (operating a motor vehicle while intoxicated)
  • OWI (operating while intoxicated), and
  • OUI (operating under the influence).

Regardless of the acronym, the meaning is generally the same: driving under the influence of alcohol or drugs.

Drunk Driving

Don’t make the mistake of confusing a DUI with “drunk driving.” If you’re arrested for a DUI, the state prosecutor doesn’t need to prove you were “drunk.” Generally, all the state has to show is that you drank enough booze or took enough drugs so that your ability to control the motor vehicle was impaired.

In fact, the prosecution typically doesn’t even need to show that you were actually impaired—for instance, even if you were driving very safely, you’ve committed a DUI by operating a vehicle with a BAC of, say, .10% (see above).

Implied Consent

Every state has implied consent laws that generally require a driver to submit to a chemical test when law enforcement is investigating a potential DUI. Drivers can usually choose between a blood or breath test for BAC (and a blood or urine test if drugs are suspected). Some states still use urine tests in alcohol cases, though these are being phased out due to lack of reliability.

Drivers who refuse testing normally face penalties for doing so, including license suspension.

Wet Reckless

“Wet reckless” is slang for what’s generally a reduced plea agreement for a driver arrested for driving while intoxicated. Usually, under the agreement, the driver pleads to "reckless driving with alcohol involved" (hence the “wet” reference). A charge of wet reckless may be preferable to a DUI because the punishment is typically less severe. Many states don’t use or recognize the term “wet reckless,” but they might nevertheless offer the benefits of plea bargains with reduced penalties. That said, over a dozen states specifically prohibit plea bargains in DUI cases.


An ignition interlock device (IID) is similar to a breathalyzer. An IID is connected to a vehicle dashboard or another location inside the vehicle; it requires that the driver breathe into the device before starting the vehicle. If the ignition interlock device detects BAC that’s above the programmed limit, then the engine of the vehicle won’t start.

“Look Back” or “Washout” Period

The “look back” (or "washout") period is the length of time—usually five to ten years—that a prior DUI conviction stays on an offender’s record for purposes of future punishment. For example, if a driver receives two DUI convictions within four years, the earlier conviction factors into the punishment for the later offense. The court will view the case before it as a second DUI, and impose the statutorily increased penalties. (Penalties tend to increase with each subsequent conviction within the look-back period.)

Read our article on case outcomes and costs for drivers arrested for second DUI offenses.


An SR-22 is a document that verifies that someone has automobile insurance. (The “SR” stands for “safety responsibility.”) An insurance company typically prepares the SR-22 and files it with the department of motor vehicles (DMV). The SR-22 is not an insurance policy; it is evidence that the driver has a policy.

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