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The definition, charges, and penalties for driving under the influence (DUI) vary by state and depend on a number of factors.

DUI overview

DUI is an acronym for Driving Under the Influence. Every state has its own DUI laws, but in all states it comes down to two basic criteria:

  1. You must be driving a vehicle. Usually this means the police actually see you driving, but evidence that you had recently been driving is also acceptable under the law.
  2. You must have consumed alcohol or drugs. The police have a number of different ways to determine this, including breath tests, blood tests, and sobriety tests. Depending on the state, DUI can refer to being under the influence of alcohol, drugs, either alcohol or drugs, or both. Additionally, some states use different acronyms to differentiate between alcohol and drugs.

DUI based on Blood Alcohol Content (BAC)

All 50 states set the legal limit for BAC at 0.08%. Above that level, you can get a DUI even if you’re not visibly impaired. If you are a commercial driver, the limit may be lower, usually 0.04%.

BAC can be measured one of three ways:

  • Blood sample
  • Urine sample
  • Breath test With a blood sample, the level is measured directly.

For the urine and breath tests, there’s a conversion formula used to determine BAC. Because of the math involved, defense attorneys sometimes question the validity of BAC levels based on urine or breath samples.

If you refuse a BAC test, most states will automatically suspend your license.

DUI based on impairment

You can also get a DUI with BAC levels below the legal limit or after taking drugs/medications (even legal ones).

If you get pulled over, the officer may have you perform one or more field sobriety tests:

  • Stand on one leg without losing your balance
  • Walk heel-to-toe in a straight line
  • Track a slowly moving object with your eyes

They may also make note of things like whether you smell of alcohol or your speech is slurred.

States differ on how they define impairment. In some states, even the slightest impairment is grounds to convict you of a DUI. In others, the prosecutor has to show you were not able to drive with the same care as a sober person.

Penalties for a DUI

In most cases, a simple first-offense DUI (no injuries or damage) is a misdemeanor. But if someone is injured, you could be charged with a felony DUI, and reckless homicide if someone dies.

A third DUI (and sometimes even a second) may also be a felony.

You can also face serious penalties even for a misdemeanor:

  • Jail time: for a first offense, sentences may range from a few days to 6 months.
  • Fines: these vary, but expect to pay at least $100 and possibly several thousand dollars.
  • Drivers license suspension: for a first-time offense, this may last only a few weeks.
  • Ignition interlock device: this device calculates your BAC based on a breath sample. The car won’t start if your BAC is too high (often 0.02% or higher). Penalties get more severe with subsequent offenses.

Aggravated DUI, which can result from added complications such as having an especially high BAC, usually increases jail time, fines, or both. The BAC level at which extra penalties kick in varies, but tends to range between .15% and .20%.

You may also have to attend DUI classes, alcohol or drug treatment, or do community service.

Other drunk driving acronyms

Although DUI is one of the most common terms used to describe impaired driving, some states use others, either in addition to or instead of DUI:

  • DWI, or Driving While Intoxicated
  • OUI, or Operating Under the Influence
  • OWI, or Operating While Intoxicated
  • OMVI, or Operating a Motor Vehicle While Intoxicated
  • OVI, or Operating a Vehicle Impaired
  • DUIL, or Driving Under the Influence of Liquor In many cases, they all mean the same thing: driving after drinking enough alcohol or taking enough drugs to make you unsafe to drive. But in some states, DUI and DWI are two different charges.

States may also use these acronyms in an effort to better describe the offense. For example, Ohio previously used OMVI but changed its laws to include non-motorized vehicles, like bicycles, so it started using OVI instead.

If you’ve been charged with a DUI, a lawyer can help you sort out your options based on your state’s laws.

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