When it comes to DUI defense, the smallest details often make the biggest difference. In a recent case defended by Torrance DUI Attorney Matthew Ruff, a client’s commitment to dental hygiene—and a poorly timed rinse—turned a likely conviction into a hung jury and a favorable resolution.

The Stop: Speeding and Signs of Trouble

The incident began when police pulled over the client for speeding. Upon approaching the window, the officer noted the “textbook” signs of intoxication:

• An odor of alcohol emitting from the vehicle.

• Slurred speech.

• Slowed responses.

The client was asked to exit the vehicle to perform Field Sobriety Tests (FSTs). According to the officer’s report, the client failed to perform the tests as instructed, leading to an immediate suspicion of impairment.

The Science: A .12% BAC and the “Mouth Alcohol” Problem

The client submitted to a breath test, which returned results of .12% and .13%—well above the legal limit of .08%. On the surface, it looked like an open-and-shut case for the prosecution. However, Matthew Ruff dug deeper into the timeline of the evening.

The “Infection Prevention” Factor

The client had recently undergone a tongue piercing. To prevent infection, his piercer had strictly advised him to rinse his mouth frequently with Listerine. Moments after being pulled over, the client—anxious about both the piercing and a beer he had consumed earlier—used the mouthwash he kept in his car to “mask” his breath.

The Defense Strategy: Contamination

Matthew Ruff successfully argued that the breathalyzer results were scientifically unreliable due to Mouth Alcohol Contamination.

Most breathalyzers operate on the assumption that the alcohol being measured is “alveolar air” (air from deep within the lungs). However, Listerine contains a high percentage of alcohol. If a subject uses mouthwash immediately before a test, the device measures the concentrated alcohol vapors in the mouth rather than what is in the bloodstream.

The Argument: The .12% reading wasn’t a reflection of the client’s blood alcohol level, but rather a measurement of the Listerine he had just swished to protect his new piercing.

The Result: From DUI to Public Intoxication

The jury was presented with the scientific possibility that the breath results were inflated by the mouthwash. After deliberations, the jury was unable to reach a unanimous verdict, resulting in a hung jury.

Recognizing the weakness in their case following the trial, the District Attorney chose not to pursue a second DUI trial. Instead, they offered a significantly reduced charge:

• Original Charge: DUI (.08% or higher)

• Final Resolution: Public Intoxication (Non-driving related)

The Takeaway

This case highlights why “objective symptoms” aren’t always what they seem. Slurred speech can be caused by a swollen, newly-pierced tongue, and high breath test results can be caused by something as simple as hygiene.

If you’re facing a DUI charge where the numbers don’t seem to add up, you need an attorney who understands the science behind the machines. Top Tier DUI Attorney Matthew Ruff continues to prove that a meticulous defense can dismantle even the most “solid” police evidence.

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