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Missouri DUI Breath Testing

Eisenhauer Law  June 20, 2024

Driving under the influence (DUI) is a serious offense in Missouri, and one of the primary tools law enforcement uses to determine a driver's level of intoxication is breath testing.  

Understanding how DUI breath testing works, as well as its implications, can help you better understand the charges if you ever find yourself facing such a situation. 

Thankfully, our legal team at Eisenhauer Law in St. Louis, Missouri has the reliable representation you need to craft a strong defense against your charges. 

DUI Laws in Missouri

Missouri has strict laws in place to deter driving under the influence. It is important to be aware of these regulations to understand the potential penalties and legal procedures you might face. 

  • Blood alcohol concentration (BAC) limits: The standard limit is 0.08% for drivers over 21 years old and 0.02% for drivers under 21 years old. Commercial drivers are limited to 0.04% for commercial vehicle operators. 

  • Implied consent law: By obtaining a Missouri driver's license, you automatically consent to submit to chemical tests (breath, blood, urine) if suspected of DUI. 

  • Penalties for DUI: The first offense is up to 6 months in jail, a fine of up to $500, and a 30-day license suspension. The second offense is up to 1 year in jail, a fine of up to $1,000, and a one-year license revocation. A third offense (as well as any subsequent offenses) has the potential for felony charges, with increased jail time, fines, and longer license suspension/revocation periods. 

  • Aggravating factors: Higher BAC levels, having a minor in the vehicle, causing injury or death, and prior DUI offenses can all lead to harsher penalties. 

Understanding and adhering to these laws is crucial, as DUI convictions can have long-lasting impacts on one's life and criminal record. 

How Breath Testing Works

DUI breath tests, commonly known as breathalyzers, are designed to measure the amount of alcohol in your breath to determine your blood alcohol concentration (BAC). Here's a detailed overview of how the process typically works: 

Pre-Test Instructions:  

  • The officer will initially inquire if you have consumed any alcohol, food, or other substances that might affect the test results. This is crucial as certain foods and substances can influence the accuracy of the breathalyzer. 

  • You may be asked to wait for a specific period if you have consumed something recently. This waiting period ensures that any residual alcohol in the mouth does not affect the outcome of the test. 

Blow into the Device: 

  • You will be instructed to blow into the breathalyzer using a mouthpiece. It is vital to follow the officer's instructions precisely, which typically require you to take a deep breath and blow steadily for several seconds. 

  • The device needs a sufficient breath sample to provide an accurate reading. Insufficient or improper breathing can lead to inaccurate results or require retesting. 

Analyzer Processing: 

  • Once the breath sample is provided, the breathalyzer uses an internal sensor to detect the amount of alcohol vapor in the breath. This is commonly done through fuel cell technology or infrared spectroscopy. 

  • For fuel cell technology, the breath sample passes through a fuel cell sensor, which generates an electrical current proportional to the amount of alcohol in the breath. The stronger the current, the higher the BAC. 

  • Infrared spectroscopy involves passing the breath sample through a chamber exposed to infrared light. The device measures how much light is absorbed by the alcohol molecules in the breath, and this absorption is translated into a BAC reading. 

Understanding how breath testing works can help demystify the process and highlight the importance of accurate testing methods in DUI cases. 

Reliability of Breath Tests

While breath tests are widely used, their accuracy can be influenced by several factors: 

  • Calibration: Breathalyzers must be regularly calibrated and maintained to provide accurate results. Calibration ensures the device measures the correct concentration of alcohol in the breath sample. Over time, sensors can drift, leading to incorrect readings, so periodic calibration checks are crucial for maintaining reliability. 

  • External factors: Temperature, humidity, and even certain medical conditions can affect the test results. For example, high ambient temperatures can increase the volatility of alcohol, potentially leading to higher readings. Humidity can also impact the breath sample's moisture content, affecting the sensor's response. Medical conditions such as diabetes can cause ketones, which some tests might misinterpret as alcohol, resulting in false positives. 

  • Consumption factors: Alcohol in mouthwash, breath sprays, and certain medications can also skew the results. Residual alcohol from these sources can linger in the mouth and airways, leading to elevated readings. It’s important to wait for an appropriate period after using such products before taking a breath test to avoid false positives. Additionally, certain foods and beverages might contain small amounts of alcohol that can affect the test results. 

Understanding these factors is crucial for interpreting breath test results accurately, ensuring they are used effectively in both medical and legal contexts. 

Legal Consequences of a DUI Breath Test 

The results of a DUI breath test can have significant and far-reaching legal consequences: 

Immediate License Suspension 

If your blood alcohol concentration (BAC) exceeds the legal limit, your driver's license may be suspended immediately, often on the spot, by law enforcement officers. This administrative suspension typically occurs before any court hearing and can last anywhere from a few months to over a year, depending on the jurisdiction and the specifics of the offense. 

In some cases, you may be eligible for a conditional or restricted license, which allows limited driving privileges, such as commuting to work or attending mandatory classes. Obtaining this type of license usually requires the installation of an ignition interlock device (IID) on your vehicle. 

Charges and Penalties 

  • Fines: DUI convictions can result in substantial fines, which can vary widely based on the severity of the offense, prior DUI history, and state laws. These fines can range from a few hundred dollars to several thousand. 

  • Alcohol education programs: Courts often mandate attendance in alcohol education or rehabilitation programs. These programs can span several weeks to months and aim to address alcohol dependency and promote safer driving habits. 

  • Community service: Many jurisdictions impose community service requirements as part of the sentencing. The number of hours required can vary but often serves as an alternative to incarceration. 

  • Jail time: Depending on the severity of the offense and whether it's a repeat violation, DUI convictions can potentially lead to jail time. First-time offenders may face shorter sentences or probation, while repeat offenders or those with exceptionally high BAC levels may face longer incarceration periods, potentially extending to several years. 

  • Criminal record: A DUI conviction often results in a permanent criminal record, which can affect future employment opportunities, professional licenses, and personal reputation. 

  • Increased insurance premiums: Post-conviction, drivers typically experience a significant increase in their auto insurance premiums. Some insurance companies may even choose to cancel the policy altogether, deeming the driver too high-risk. 

Understanding these consequences underscores the importance of responsible driving and the serious repercussions of DUI offenses. 

What To Do If You Dispute the Results 

Disputing the results of a breath test can be a complex process, but there are several steps you can take to ensure a thorough examination of the situation: 

1. Request a Blood Test 

A blood test is often more accurate than a breath test and can provide a precise measurement of your Blood Alcohol Content (BAC). Blood tests can also detect the presence of other substances that may have influenced your BAC reading. 

It's crucial to request this test as soon as possible to ensure the results are relevant and reflective of your actual BAC at the time of the incident. 

2. Consult a DUI Attorney 

Consulting with an experienced criminal defense attorney can help you understand your rights and the nuances of DUI laws. An attorney can scrutinize the breath test's validity by examining the device used, the maintenance records, and whether it was properly calibrated. 

They can also investigate the protocol followed during the test to ensure it adhered to legal standards and procedural accuracy and explore possible defenses, such as medical conditions that could have affected the breath test or the presence of residual mouth alcohol. 

Additionally, an attorney can guide you through the legal process, represent you in court, and negotiate on your behalf for reduced charges or alternative sentencing options. 

3. Gather Evidence 

Collect any evidence that can support your dispute of the breath test results. This includes eyewitness testimony, video footage, or any other relevant documentation. Be sure to keep records of your activities leading up to the incident, as this can provide context and support for your case. 

4. Understand Your Rights 

Familiarize yourself with the legal implications of refusing a breath test, as this can vary by jurisdiction and may carry its own set of penalties. Be aware of your right to challenge the evidence against you and to request a hearing to dispute the breath test results. 

By taking these steps, you can build a robust defense and ensure that your rights are protected throughout the legal process. 

Common Defenses Against DUI Charges

When facing DUI charges based on breath test results, several defenses might be applicable: 

  • Questioning the test's accuracy: Breath test results can be challenged on the grounds of improper calibration of the device. Breathalyzers must be regularly maintained and correctly calibrated to provide accurate readings. External interference, such as radio frequency interference or the presence of certain chemicals, can also impact the accuracy of the test. The time elapsed between the alleged offense and the administration of the test may also affect the results. 

  • Medical conditions: Certain medical conditions can result in false positives on a breathalyzer test. For instance, individuals with acid reflux or gastroesophageal reflux disease (GERD) may have alcohol vapors from their stomachs rise to their mouth, which can be detected by the breathalyzer and cause an inflated reading. Diabetes can also be a factor, as some diabetics produce acetone, which breathalyzers may mistake for alcohol. 

  • Administering errors: Administering a breathalyzer test is strictly regulated, and any deviation from the prescribed procedure can render the results invalid. This can include errors such as the officer not observing the individual for a required period before administering the test, not following proper protocol during the test, or using a device that has not been properly certified. If the officer lacks proper training or credentials, this can be grounds for challenging the results. 

By thoroughly examining these potential defenses, individuals facing DUI charges can build a more robust case to dispute the allegations against them. 

Strong & Reliable Legal Representation

DUI breath testing is a critical component in Missouri's efforts to combat drunk driving. However, these tests are not infallible, and understanding their limitations can be essential for your defense.

At Eisenhauer Law, we are committed to helping clients navigate DUI charges and achieve the best possible outcomes. If you are facing a DUI charge in Missouri, contact us today to discuss your case and explore your defense options.