Impaired Driving: Laws, Penalties and Consequences
DUI & DWI Laws and Facts

DUI or DWI: Understanding DUI & DWI Laws, Sobriety Checkpoints

Updated Dec. 25, 2020

DWI (driving while intoxicated) and DUI (driving under the influence) can be confusing terms for new and experienced motorists alike! Both phrases refer to driving a vehicle while intoxicated by alcohol or drugs, and many states use them interchangeably. The term “driving while intoxicated” was originally introduced to make it easier to prosecute alcohol-impaired drivers. While it is not always easy to determine what constitutes “impaired driving”, the law in all 50 states defines “intoxicated” as having a BAC of 0.08% or above. Therefore, any driver with a BAC of 0.08% will automatically be charged with DWI, whether they are showing signs of alcohol impairment or not.

Quite a few states use the terms DWI and DUI to distinguish between two separate impaired driving offenses. In these instances, DUI may refer to driving under the influence of drugs, while DWI refers to driving while intoxicated by alcohol, or vice versa. You can find out how these terms relate to impaired driving offenses in your state by checking out the state’s penal code or your driver’s education materials. A few state-specific examples of DUI and DWI laws will be included below.

Other states do not distinguish between impairment by alcohol and impairment by drugs, using the two terms to denote levels of intoxication instead. In this case, “driving under the influence” infers a lesser degree of impairment and is considered a less serious offense than DWI. In these jurisdictions, drivers with blood alcohol concentrations above the legal limit are usually charged with the more serious offense of DWI. Depending on the severity of the offense, the guilty driver may be offered a plea bargain to reduce their charge from DWI to DUI.

The DUI/DWI distinction prevents drivers who are noticeably impaired but are NOT over the legal BAC limit from escaping prosecution. The bottom line is that you will be charged with DUI or DWI if:

  • Your BAC is 0.08% or above, and/or
  • You have tested positive for illicit drugs, and/or
  • You are displaying signs of impairment (usually this means performing poorly during a field sobriety test)


OUI (operating under the influence) and OWI (operating while intoxicated) are two other acronyms you may encounter which refer to impaired driving offenses. Maine, Massachusetts and Rhode Island all use these terms to prosecute drivers who are caught operating a vehicle while intoxicated. In these cases, the perpetrator can be charged simply for sitting in the driver’s seat of a parked vehicle with the engine running, while under the influence of alcohol or drugs.

Sobriety checkpoints

Many states use sobriety checkpoints as a tactic to catch and deter impaired drivers. At a sobriety checkpoint, law enforcement officers will set up a roadblock on a public roadway and test a random selection of drivers for signs of alcohol or drug-impairment. This may include questions, a field sobriety test, a breathalyzer test or all the above. Sobriety checkpoints must be advertised prior to their establishment (usually on the radio, in a local newspaper or with signs set up on the road itself) and must choose drivers at random, to be deemed legal under federal law. To keep the process random, police officers will often predetermine a pattern to follow when testing drivers – for instance, every fifth vehicle.

Sobriety checkpoints are not currently conducted in Alaska, Iowa, Michigan, Minnesota, Oregon, Rhode Island, Washington, Idaho, Texas, Wisconsin, Wyoming or Montana (though, Montana does permit “safety spot checks”). States that prohibit sobriety checkpoints generally do so because they believe the practice to be in violation of the state or federal constitution, or because random searches are illegal under state law.

DUI and DWI laws

Here are some examples of the rules concerning DWI and DUI convictions in a few states, to give you an idea of how they vary:


In Texas, the term driving under the influence (DUI) is reserved exclusively for minors who are caught driving under the influence of alcohol. As persons under 21 years old are not permitted to drive with any amount of alcohol in their system, they qualify as “influenced” by alcohol if their BAC is 0.01% or above.

“Driving while intoxicated” refers to all other drug and alcohol impairment convictions. An adult driver will be charged with DWI if they have a BAC of 0.08% or above or are mentally or physically impaired by alcohol or another controlled substance.

New York

New York uses the term DWI to refer to all alcohol and drug-impairment cases. However, DWI infers a case of considerable intoxication; usually, the driver in question would be over the legal BAC limit or displaying signs of serious impairment. The less serious charge of DWAI (driving while ability-impaired) may be used when a driver is impaired by alcohol or drugs to a lesser extent. This would usually only be an option if the driver is not over the legal BAC limit and has not tested positive for illegal substances. In New York, drivers under 21 years old with a BAC level of 0.02% or higher will be charged with DWI.


The legal BAC limit in Utah is 0.05%. Any adult driver caught with a BAC of 0.05% or above, or who is under the influence of alcohol or drugs, will be charged with DUI. The term DWI is not commonly used in this state.

In Utah law, a person qualifies as “under the influence” if they have any amount of drugs or alcohol in their system and are “physically incapable of operating a vehicle safely”. This definition would allow a person to be prosecuted for DUI while under the influence of legal, non-prescription drugs such as cold remedies, caffeine and nicotine if they were displaying obvious signs of impairment.


In Maryland, DWI stands for “driving while impaired” and is considered a less serious offense than DUI. A person may be charged with DWI if they are displaying signs of impairment (such as erratic driving or failing a sobriety test) but have passed a breathalyzer test with a BAC reading just below the legal limit of 0.08%. DUI refers to incidences of alcohol impairment when the driver’s BAC is 0.08% or above.

Understanding DUI laws

As a new driver, you must know the DUI laws (and how they are enforced) in your state. When you’re done reading this module, check your driver’s handbook or the DMV website for information relevant to your area. Make sure you check this information whenever you are traveling to an unfamiliar state too. As you can see from the above examples, the definition of alcohol and drug-impairment can vary quite a bit from one state to another. There are also considerable differences in the penalties incurred for DUI and DWI in different states, which is the topic of discussion in our next module.

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