Common Defenses DUI Lawyers Use To Fight Charges

Being charged with Driving Under the Influence (DUI) can be a frightening and overwhelming experience. The potential consequences—license suspension, fines, increased insurance rates, and even jail time—can have a lasting impact on your life. However, a DUI charge is not the same as a conviction. With the help of a DUI lawyer, there are several legal defenses that can be used to challenge the case and potentially reduce or dismiss the charges.

Below are some of the most common DUI defenses lawyers use to protect their clients.

Unlawful Traffic Stop

One of the first things a DUI lawyer will investigate is whether the police had a valid reason to pull you over. Law enforcement must have “reasonable suspicion” of a traffic violation or criminal activity to make a stop. If the officer lacked probable cause—such as swerving, speeding, or running a red light—the entire case could be thrown out because the stop itself was unconstitutional.

Improper Field Sobriety Tests

Officers often use field sobriety tests (FSTs) such as the walk-and-turn or one-leg stand to assess impairment. However, these tests are subjective and prone to error. Many factors—such as fatigue, medical conditions, uneven pavement, or poor footwear—can affect performance. A DUI lawyer can argue that the results were unreliable or that the officer administered the tests improperly.

Inaccurate Breathalyzer Results

As our friends at Rasmussen & Miner can attest, breathalyzer machines must be properly calibrated and maintained to produce accurate results. Even then, various factors like medical conditions (e.g., acid reflux), certain diets (e.g., keto), or even mouthwash can lead to false positives. A skilled DUI attorney can challenge the accuracy of the breath test and question whether it was administered according to regulations.

Faulty Blood Test Procedures

If you were given a blood test, the prosecution must prove that the sample was collected, stored, and analyzed following strict protocols. Any mishandling—such as contamination, expired test kits, or chain-of-custody issues—can call the results into question. A DUI lawyer may file a motion to suppress improperly handled evidence.

Lack Of Probable Cause For Arrest

Even if the traffic stop was legal, the officer must still establish probable cause before making an arrest. This means they need clear signs of intoxication, not just a hunch. If the arrest was based on vague or insufficient observations, a lawyer can argue that your rights were violated, which may lead to the suppression of key evidence.

Medical Or Physical Conditions Mistaken For Impairment

Certain medical conditions—like diabetes, neurological disorders, or even anxiety—can mimic the signs of intoxication (e.g., slurred speech, imbalance). A DUI lawyer may present medical records or expert testimony to explain how these conditions could have been misinterpreted by the arresting officer.

A DUI charge doesn’t automatically mean you’ll be convicted. With the right legal strategy, it’s possible to challenge the prosecution’s evidence, suppress unreliable test results, or even get the case dismissed entirely. Each case is unique, and a DUI lawyer will thoroughly investigate the facts, identify weaknesses in the prosecution’s case, and fight aggressively to protect your rights.