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DUI/DWI Defenses

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A conviction for driving under the influence can translate into a jail sentence, financial hardship, loss of license and other potentially serious consequences. However, there are many DUI defenses that may be put forth to reduce or even dismiss the charges. For example, if evidence was gathered following an unlawful stop, search or seizure, it may not be admissible in a court of law. If your BAC was above the legal limit (.08) you may not have been intoxicated; a medical condition or faulty machine might be to blame. Even if you were legally impaired, you may have had a medical emergency or other good reason to be behind the wheel.

If you are facing a DUI charge — regardless of whether it is a first offense or repeat violation — contact an experienced attorney to evaluate your case and minimize your cost for driving while intoxicated.

Constitutional and Statutory Rights

A DWI/DUI investigation typically begins with a traffic stop, search and seizure of evidence, and finally, an arrest and interrogation. Throughout this process, the defendant has legal rights under the Constitution. If your rights or state laws are violated, the evidence (and possibly the case) may be dismissed.

Unlawful Stop. The Fourth Amendment to the United States Constitution protects you from unreasonable search and seizure. Accordingly, evidence collected by the police as a result of an unlawful stop violates your Constitutional rights and is inadmissible in a court of law.

  • Traffic Stops. The police cannot pull someone over based on a hunch — they must have a reasonable suspicion a crime (e.g., traffic violation) is being committed for a traffic stop to be lawful.
  • Sobriety Checkpoints. A few states don't allow sobriety checkpoints, and those states that do generally have rules that must be strictly adhered to. Guidelines vary by state but may include certification requirements and advance notice to the public. To learn more about your state's laws concerning sobriety checkpoints, contact a DWI/DUI attorney.

Unlawful Search & Seizure. During a lawful traffic stop, the police may observe and question you. However, the police cannot search you or your car (without your consent) or arrest you without probable cause. This means they must not only suspect but also have a reasonable belief that a crime has or is being committed. For example, if a driver has an open container of alcohol visible to the officer during a lawful traffic stop, the officer may have probable cause for DWI/DUI. However, if the container was not visible and the officer searched the car without probable cause, a DWI/DUI attorney might be able to get the case dismissed.


Violation of Miranda Warnings. "You have the right to remain silent. Anything you say can be used against you in a court of law. You have the right to have an attorney. If you cannot afford an attorney, one will be appointed for you at no cost." These well-known "Miranda Warnings" stem from the Fifth Amendment right against self-incrimination and apply during all interrogations subsequent to an arrest. If the police did not inform you of your rights, or if they violated your rights by questioning you after you asked for an attorney, any statements you made can be suppressed.

If any of your rights were violated during a stop, search or arrest process, an experienced DWI/DUI attorney may be able to get the case dismissed. Considering the severity of most DUI penalties — which can include everything from DUI bail cost and associated legal fees to loss of work and jail time — it is important to take immediate action in your case. (Learn more about how a DWI bail bondsman can help you.)

Personal Injury and Wrongful Death Lawsuits

A motorist accused of DWI/DUI not only faces possible criminal charges, but also may be sued for personal injury or wrongful death damages. Notwithstanding, the injured plaintiff may have been partly or completely responsible for his or her injuries which can lessen or eliminate an award for damages. Some states, including North Carolina, Virginia, Maryland, Alabama and the District of Columbia, allow a defendant to argue contributory negligence if the plaintiff knew or should have known the driver was intoxicated. In comparative negligence states, the amount of the award is reduced based on the degree of fault assigned to the plaintiff. The defense can also argue "assumption of risk" if the plaintiff had knowledge of the risk of danger, appreciated that risk, and voluntarily confronted the risk of danger.


If your BAC tested above the legal limit, you can, in some cases, challenge the accuracy of the breath, blood or urine test results. It is possible to be charged with DUI/DWI with a BAC under .08, but the prosecution needs evidence beyond a reasonable doubt that you were impaired in order to get a conviction. Field sobriety test results can be used as evidence to support the prosecution, but these tests are subjectively interpreted and vulnerable to improper administration.

Field Sobriety Tests. Field sobriety tests are roadside physical and psychological tests (e.g., stand on one leg) to help the police determine whether a motorist is under the influence of drugs or alcohol. Some of the common challenges defendants raise with respect to field sobriety test results include:

  • Officers having inadequate training and certification to perform field sobriety tests
  • Medical conditions (e.g., multiple sclerosis)
  • Emotional state during the testing (anxious, nervous, angry)
  • Wet, slippery or uneven road conditions
  • Bad footwear (e.g., stiletto heels, boots or dress shoes)
  • Difficult environment (e.g., glaring headlights or distracting police car flashers)
  • Bad weather

Chemical Tests. Blood tests, urine tests and breath analyzers such as the Breathalyzer are all used to determine BAC. It is not illegal to have a BAC of .08 or higher at the time of testing, only at the time of driving. It is important to analyze any time delays between the stop and the subsequent test. Since it can sometimes take hours for alcohol to be absorbed into the blood, the "rising blood alcohol defense" can be a particularly important defense when there is a delay between the stop and the test. Other ways to challenge the results of a BAC include:

  • Alcohol in your mouth or throat from cough drops, asthma medications and other products, which can artificially inflate a breath analyzer result
  • The testing device was not properly calibrated or maintained
  • The person who administered the test was not properly trained
  • A pre-existing medical condition (e.g., acid reflux disease)
  • Radio frequency interference

A DWI/DUI attorney will examine whether the tests were administered properly and whether the results were correctly interpreted.

Affirmative Defenses

Depending on the facts and circumstances, there are several other approaches your attorney will consider in defending a DWI/DUI charge. These strategies may include:

  • Involuntary intoxication. This defense may apply if you ingested alcohol without your knowledge.
  • Duress. This defense may apply if you had a reasonable fear of serious bodily harm (for example, you were being chased by someone armed with a dangerous weapon) and had no reasonable legal alternative.
  • Necessity. This defense may apply if you drove while intoxicated out of necessity, such as a medical emergency.
  • Entrapment. This defense may be raised if a law enforcement official induced or persuaded you to drive while under the influence of drugs or alcohol.

The requirements for affirmative defenses vary by state. A DWI/DUI attorney in your jurisdiction can best evaluate whether any of these defenses can be raised on your behalf.

A good defense attorney may also be able to strengthen your defense by challenging the credibility of prosecution witnesses and calling witnesses to testify that you were not drinking or using drugs. Contact a DUI attorney as soon as possible.