All states have laws prohibiting driving under the influence (DUI)—also called “DWI” (driving while intoxicated), “OUI” (operating under the influence), and “OWI” (operating while impaired)—of drugs and alcohol. Here are the basics on how the crime is defined and some of the possible penalties for a DUI conviction.

Determining Intoxication

DUI laws are aimed at preventing motorists from getting behind the wheel in an impaired state. And law enforcement officers in every state use similar tools to enforce DUI laws and detect impairment—things like DUI checkpoints, field sobriety tests (FSTs), breathalyzers, and blood tests. But when it comes to how impairment is defined, there are commonalities and differences among the states.

Drugs and Alcohol

Generally, DUI laws apply whether the driver’s impairment was due to alcohol or some other substance. So, you can be charged with DUI for driving while under the influence of alcohol, drugs, or a combination of the two. And it typically doesn’t matter if the drug ingested was illegal, over-the-counter medication, or prescribed by a doctor—if the motorist was impaired, lawful use generally isn’t a defense to DUI charges.

“Per Se” Intoxication

All states have “per se” DUI laws. Generally, these laws make it illegal to drive with a blood alcohol concentration (BAC) of .08% or more. (But how many drinks it takes to hit the legal limit varies depending on a number factors.) The only exception being Utah, which currently has a per se limit of .05%.

Some states also have drug per se DUI laws. In states that have these laws, motorists can be convicted of DUI for having a certain amount of drugs their bodies. Per se drug DUI laws typically apply only to illegal drug use. So, if you have a prescription for a medication, you can be convicted of DUI only if you’re actually impaired.


DUI laws in every jurisdiction also prohibit driving while impaired by alcohol, drugs, or other intoxicating substances. However, impairment DUI laws differ in how they define impairment. In some states, a driver is considered impaired if affected even to the slightest degree by drugs or alcohol. But in other states, the alcohol or drugs ingested must have a substantial effect for the motorist to be guilty of DUI.


Depending on the circumstances, a DUI can be either a misdemeanor or felony—meaning the potential penalties will differ significantly based on the facts of the case. Penalties will also differ depending on the state in which the crime is charged. Nevertheless, DUI convictions will typically bring one or more of the following penalties.

  • Prison or jail. It’s very common for someone convicted of a DUI to have to serve at least some time in jail. Misdemeanor charges generally can result in up to a year in jail, while a year or more in the state prison is possible for anyone convicted of a felony DUI.
  • Fines. In addition to incarceration, someone convicted of DUI will also likely have to pay a fine. Fine amounts differ widely, ranging from a few hundred dollars for first-time misdemeanor convictions to up to $10,000 or more for a felony conviction.
  • Probation. In many DUI cases, the judge sentences the offender to complete a term of probation. Probation usually lasts at least 12 months, but terms of probation of up to three years or more are also possible. While on probation you must agree to abide by a range of court required conditions. If you fail to meet these obligations, the court can impose additional penalties. Probation conditions differ but might involve meeting regularly with a probation officer, agreeing to submit to random drug and alcohol testing, completing a substance abuse program, and not committing crimes or drunk driving offenses during probation.
  • License suspension. A DUI arrest—even if you’re never convicted in criminal court—often leads to an administrative license suspension from the Department of Motor Vehicles (DMV). Depending on the circumstances, administrative suspensions typically range from three months to several years. And if you are ultimately convicted of DUI in court, the judge will likely impose a license suspension of about the same length. However, the suspensions are often allowed to overlap—meaning the motorist doesn’t have to complete the cumulative total of the two suspensions. Some states also allow motorists to apply for a “restricted” or “hardship” license to drive to and from places like work and school during the suspension period.

DUI Laws by State

Each state has its own specific laws and penalties for driving under the influence. Learn more about the DUI laws in your state at

Obtain Legal Advice From a Local Attorney

Even though DUI charges are fairly common in any jurisdiction, these crimes can be very complicated and involve questions about evidence, procedure, and legal precedent. Because each state has a slightly different DUI law, anyone charged with this crime needs to speak to a local criminal defense attorney. These lawyers will not only be experienced with the relevant laws but will also have experience with area courts, prosecutors, as well as the procedures local police use when investigating DUI crimes. You need to speak to a local defense attorney as soon as you are charged with any DUI crime. If you delay, even a short amount of time, this can seriously affect your case and your ability to defend against the charges.