Why Did I Get a False Positive From a Breathalyzer Test

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Breathalyzers are a common tool for law enforcement to assess impairment due to alcohol. While designed to measure blood alcohol concentration, their accuracy can be influenced by a variety of factors, from device calibration to the individual’s physiology.

Arizona law, under ARS 28-1381, stipulates that driving under the influence of intoxicating liquor with a BAC of 0.08% or higher is illegal. However, the reliability of the breathalyzer test used to determine this BAC is not absolute.

This article will cover the following topics:

officer conducting breathalyzer test

How Accurate are Breathalyzers 

Breathalyzers are important tools in law enforcement’s arsenal for determining a driver’s sobriety. These devices are designed to measure the amount of alcohol in one’s breath, thereby estimating the blood alcohol content (BAC). However, the accuracy of breathalyzers can vary based on several factors including:

Technology and Functionality

Breathalyzers operate on the principle that the alcohol in your breath correlates with your blood alcohol level. This is based on the scientific premise of the blood-breath ratio. However, this ratio can vary among individuals and under different circumstances, which can affect the device’s accuracy. Moreover, there are different types of breathalyzers, including semiconductor oxide-based and fuel cell-based, each with varying degrees of precision and susceptibility to external factors.

Calibration and Maintenance

The accuracy of a breathalyzer significantly depends on its calibration and maintenance. Arizona law requires regular calibration and maintenance of these devices to ensure accurate readings. If a device is poorly maintained or improperly calibrated, it can lead to incorrect BAC readings. Defense attorneys often scrutinize the maintenance records of breathalyzer devices when challenging DUI charges based on their readings.

User and Environmental Factors

Several user-related and environmental factors can also impact the accuracy of breathalyzer tests. For example, the timing of the test relative to the last drink consumed can dramatically alter the BAC reading due to residual mouth alcohol. Additionally, the individual’s body temperature, breathing pattern, and even diet can affect the results. Environmental factors, such as the presence of certain chemicals or fumes, can also cause false positives.

Scientific Studies and Standards

Scientific studies have shown varying results regarding breathalyzer accuracy.

Some studies suggest that breathalyzer tests can have a margin of error up to ±0.01% BAC.

The legal limit is 0.08%, so a margin can be significant. Furthermore, national standards, such as those set by the National Highway Traffic Safety Administration (NHTSA), provide guidelines for breathalyzer accuracy and usage.

Reasons For a False Positive Breathalyzer Test

A false positive breathalyzer test can be a big issue in DUI cases, leading to unwarranted legal consequences for individuals.

Here are some common factors contributing to false positive readings:

  1. Mouth Alcohol: Residual alcohol from food, drinks, or mouthwash can remain in the mouth and lead to inflated BAC readings.
  2. Medical Conditions: Conditions such as acid reflux, GERD, hiatal hernia, or diabetes can produce substances in the breath that are misinterpreted as ethyl alcohol by breathalyzers.
  3. External Factors and Substances: Exposure to volatile compounds from substances like paint thinner, gasoline, or cleaning fluids can result in false positives. Environmental conditions, such as temperature and humidity, can also affect the results.
  4. Improper Use or Device Malfunction: Incorrect operation of the breathalyzer by law enforcement or malfunctioning of the device due to poor maintenance or calibration can compromise test accuracy.
  5. Diet and Other Factors: Diets high in protein and low in carbohydrates can increase ketone production, which can be mistaken for alcohol. Foods fermented with yeast and sugar-free products containing sugar alcohols can also lead to false positives.

Each of these factors can contribute to a false positive result in breathalyzer tests, underscoring the importance of accurate administration and interpretation of results, especially in the context of DUI charges under Arizona law.

food that raises bac content

Foods That Can Cause a False Positive 

Certain foods and dietary products can inadvertently impact breathalyzer test results, leading to false positives. 

 Here’s a list of common culprits:

  1. Ripe Fruits and Fruit Products: Some fruits, especially those that are overripe, can ferment inside the body and produce alcohol as a byproduct. This internal fermentation can lead to higher breathalyzer readings.
  2. Bakery Products: Foods like bread, pastries, or pizza dough contain yeast. Yeast can ferment sugars in the food, creating alcohol. If consumed shortly before a breathalyzer test, these foods might skew the results.
  3. Sugar-Free Products: Many sugar-free products contain sugar alcohols like xylitol, sorbitol, or mannitol. These substances can be misinterpreted as ethyl alcohol by certain types of breathalyzers.
  4. Protein Bars: Some protein bars and health food products may undergo fermentation, which can produce trace amounts of alcohol.
  5. Medicinal Syrups and Mouthwash: While not foods, it’s important to note that these products often contain alcohol and can linger in the mouth, leading to false readings.
  6. Vinegars and Fermented Sauces: Condiments like ketchup, soy sauce, or balsamic vinegar may contain fermented elements that could affect breathalyzer outcomes.
  7. Energy Drinks: Certain energy drinks may contain ingredients that alter metabolism or mimic the presence of alcohol in the breath.

Can a False Positive Lead to a DUI Charge 

A false positive on a breathalyzer can indeed lead to a DUI charge in Arizona. Under state law, a driver can be charged with DUI if a breathalyzer incorrectly indicates a BAC above the legal limit of 0.08%.

However, the state’s DUI statutes extend beyond conventional BAC levels, encompassing what is known as “impairment to the slightest degree.” This means that even if your BAC is below 0.08% or if there’s a false positive, you can still face DUI charges if the officer believes your ability to drive was impaired in any way.

However, it’s important to understand that a DUI charge based on a false positive is not definitive and can be contested in court. The accused has the right to challenge the breathalyzer’s accuracy, including questioning the device’s calibration, the administration of the test, and other influencing factors like diet or medical conditions that can cause false readings.

What Should I Do If I Get a False Positive on a Breathe Test

If you find yourself facing a false positive on a breath test in Arizona, taking immediate and informed action is crucial.

Here’s what you should do:

  1. Stay Calm and Polite: React calmly and respectfully during your interaction with law enforcement. Panicking or becoming combative can worsen your situation.
  2. Document Everything: Record the time, location, and circumstances of the test. Note what you ate, drank, or any substances you were exposed to prior to the test.
  3. Request a Blood Test: If possible, request a blood test to confirm your BAC level. Blood tests are generally more accurate than breath tests and can provide a clear counterpoint to a false positive breathalyzer result.
  4. Do Not Admit to Drinking: Avoid making any statements about alcohol consumption or other incriminating remarks. Under stress, you might say something that could be used against you in court.
  5. Contact an Attorney: Seek legal assistance as soon as possible. An experienced DUI attorney can help you handle the legal system, challenge the breathalyzer results, and develop an effective defense strategy.
  6. Follow Legal Advice: Cooperate with your attorney and follow their advice closely. They may suggest gathering additional evidence, such as witness statements or surveillance footage, to support your case.
  7. Prepare for Court: If your case goes to court, ensure you are prepared. Work with your attorney to understand the charges against you, the legal process, and the defense strategy.
  8. Educate Yourself: Understand the laws regarding DUI and breath tests in Arizona. Knowledge of your rights and the legal standards can be incredibly beneficial.

By following these steps, you can proactively address a false positive on a breath test and safeguard your legal rights. Remember, a false positive does not automatically mean you will be convicted of a DUI; with the right approach and legal support, you can challenge the results and strive for a favorable outcome.

person getting a blood test

Why Blood Tests are Important

Unlike breathalyzer tests, which can be swayed by factors like your diet, health conditions, or errors with the device, blood tests directly measure the alcohol in your blood. This provides a straightforward picture of your impairment level at the time of the test.

When breathalyzer results might not show the true blood alcohol concentration (BAC), blood tests become important for verifying or challenging these initial results. They are especially useful in court for proving whether someone’s impairment was due to alcohol or something else, like a medical issue.

Moreover, blood tests can help determine when alcohol was consumed

Because of their importance, blood tests are commonly used to ensure fairness and accuracy in the legal handling of DUI charges in Arizona and elsewhere.

Free Consultation with a Criminal Defense Attorney

Arja Shah | Shah Law Firm Arja Shah Law provides expert DUI defense with a personalized approach tailored to your unique situation.

With a strong track record in handling DUI cases, her dedicated team ensures every legal avenue is explored. They offer comprehensive support, from challenging test results to courtroom representation, emphasizing clear communication and client-focused strategies.

Arja Shah Law offers a free initial consultation to discuss your case without commitment. For dedicated and compassionate defense, contact Arja Shah Law at (602) 560-7408

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