What is DUI & DWI Law?

Criminal charges and the tests officers use

By Super Lawyers staff | Reviewed by Canaan Suitt, J.D. | Last updated on January 30, 2023

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If you operate a vehicle while under the influence of alcohol or some other substance, you risk being charged with a DUI (driving under the influence), DWI (driving while intoxicated), or other offense. While different in name, the charges follow a similar procedure.

These charges can range in severity depending on where you were cited and whether there were other traffic violations involved. This may be your first experience with the criminal justice system, and you might feel overwhelmed and unsure whether you can challenge any of the tests you were asked to complete. The following is designed to give you an overview of DUI/DWI charges and the tests officers use, so you feel confident speaking with a lawyer.

DUI / DWI Law – What You Need to Know

  • Drivers that operate motor vehicles under the influence of alcohol or some other substance risk not only DWI and DUI charges from law enforcement but also the safety of other motorists.
  • These charges can be misdemeanors or felonies depending on blood alcohol concentration and mitigating circumstances such as whether this is the first offense.
  • Punishments for driving under the influence can include revocation of your driver’s license, community service, or jail time.
  • A DUI charge can have lasting effects on one’s record, so consider speaking with a criminal lawyer about next steps.


Laws about intoxicated driving tend to be state-specific. Even the name of the offense can vary from state to state. However, every state has set a limit at which you are considered legally intoxicated, even if you aren’t exhibiting signs of intoxication. This is usually referred to as “the legal limit” and is most commonly a blood alcohol content (BAC) of .08% or higher—and the percentage is often lower for commercial vehicle drivers. Some states have set their legal limits lower, and many states use other measurements to test for intoxication from illegal drugs or prescription medication.

Testing for Intoxication

If you are stopped by an officer who suspects you may be drunk driving, the officer might ask you to complete some field sobriety tests. The general field sobriety test includes the horizontal gaze nystagmus, the walk-and-turn, and the one-leg stand.

Horizontal gaze nystagmus

During this test, the officer will have you follow a pen with your eyes, and they will look for any involuntary eye movement (called nystagmus). Nystagmus is the repetitive and uncontrolled jerking of the eyes, and it is usually more pronounced when a person is intoxicated. During this test, the officer notes the angle at which a person’s eye bounces or jerks.

Walk-and-turn test

This test has two parts: the instruction and the performance. During the instruction, you will be asked to stand heel to toe and listen while the officer explains what you will do next. After the instruction, you will take heel-to-toe steps forward, turn around and walk back to your starting point. The officer will be looking for signs you may be intoxicated, such as taking the wrong number of steps, starting too soon, or stepping off the line.

One-leg stand

During this test, you will be asked to stand with one leg slightly off the ground while counting until you are asked to put your foot down. Usually, you will be asked to balance for about 30 seconds with your eyes on your elevated foot and your arms at your side. The officer will be looking for signs of intoxication, such as swaying, hopping, or putting your foot down.

These tests are all standardized, which means the officer should follow specific guidelines when administering the tests. The accuracy of the field sobriety test is highly dependent on varying factors, including whether they were administered correctly.

Chemical Tests – Breath and Blood Alcohol Tests

A police officer might also ask you to submit to a breathalyzer test, which measures the amount of alcohol on your breath. Under implied consent laws, you might face consequences for refusing a breathalyzer test as these laws mean you have consented to a blood alcohol content test in exchange for driving privileges. Some states allow you to speak with a lawyer before deciding whether to submit to a test, and you may want to consider whether that is an option for you.

In some cases, you may be asked to submit to a blood alcohol level test or urine test. These tests are generally not done on the side of the road, and each state has its own requirements for who can administer the tests and how they are analyzed.


DUI cases proceed through the legal system like most other cases in the criminal justice system. If you are charged with driving while intoxicated, you will need to be booked and informed of your charges. You will then go before a judge to enter your plea. You or your lawyer may file suppression motions to challenge the admission of any field sobriety tests you were asked to take. If these challenges are successful, it could result in your case being dismissed. It is rare for a DWI case to go to trial because most people plead to a lesser charge, usually reckless driving.


Penalties for driving while intoxicated also vary by state. You might also face enhanced penalties if there was an accident, injury, or a child in the car. Common punishments include fines, driver’s license suspension, jail time (especially if you already have a second offense on your record), treatment programs, and ignition interlock devices.

An ignition interlock device can be installed in your vehicle that includes a breathalyzer with a pre-set blood alcohol content limit. Your car will start if the breath test results are below the pre-set limit. If not, you will not be permitted to drive. Some jurisdictions require the installation of an interlock device after a specified number of DUI convictions.

Common Questions for an Attorney

Below are some common questions you might want to consider when meeting with an attorney for the first time.

  1. Are DUI checkpoints legal?
  2. Will I lose my license?
  3. Can I challenge my charge if I think the officer conducted the field sobriety tests incorrectly?
  4. How long will a DUI stay on my record?
  5. What if I don’t have a car, but the court required me to install an ignition interlock?

Finding the Right Attorney for Your Needs

Criminal law is a challenging area where the result can have lasting legal implications. It is essential to approach the right type of attorney—someone who can help you through your entire case. To do so, you can visit the Super Lawyers directory and use the search box to find a lawyer based on your legal issue or location.

To help you get started, you may want to consider looking for a criminal defense lawyer specializing in DUI/DWI law.

Why Should I Talk to a DUI Lawyer?

Even straightforward cases can be complicated, and it can be helpful to have the assistance of someone who knows the law in your state. An experienced lawyer will know the relative accuracy of the sobriety tests you were asked to take and the best way to challenge their admission. Your lawyer can discuss plea agreements for you and negotiate your penalties.

A lawyer will anticipate potential problems with your case and advise you on how to approach them. Your lawyer will also keep track of deadlines and file all the paperwork with the necessary courts and agencies, giving you one less thing to worry about.

What do I do next?

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