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The Role of Breathalyzer & Blood Test Results in DUI Cases


When facing a DUI charge, the results of breathalyzer and blood tests can have a significant impact on your case. These tests are often considered strong evidence against you, but they are not infallible. In fact, there are many factors that can affect the accuracy of these tests, and understanding these factors can help you build a strong defense. In this post, we will explore the role of breathalyzer and blood test results in DUI cases, as well as how to challenge their accuracy in court.

Understanding Breathalyzer & Blood Test Results

Breathalyzer and blood tests are used to measure the amount of alcohol in a person's system. In most states, a blood alcohol concentration (BAC) of 0.08% or higher is considered legally intoxicated. However, it is important to note that these tests are not always accurate, and their results can be influenced by various factors, such as:

  • Device calibration and maintenance
  • Operator error
  • Medical conditions
  • Environmental factors
  • Time elapsed since drinking

Because of these potential issues, it is crucial to thoroughly examine the circumstances surrounding your breathalyzer or blood test to ensure that the results are accurate and admissible in court.

Challenging the Accuracy of Breathalyzer Tests

There are several ways to challenge the accuracy of a breathalyzer test in a DUI case. Some common strategies include:

  • Questioning the device's calibration: Breathalyzers must be properly calibrated to ensure accurate results. If the device used in your case was not calibrated according to the manufacturer's specifications or state regulations, the results may be unreliable.
  • Examining operator error: The person administering the breathalyzer test must be properly trained and certified. If they made any errors in administering the test or interpreting the results, the evidence may be inadmissible.
  • Identifying medical conditions: Certain medical conditions, such as asthma, acid reflux, or diabetes, can cause false-positive breathalyzer results. If you have a medical condition that could have affected your test results, it is important to present this information as part of your defense.
  • Considering environmental factors: External factors, such as paint fumes or gasoline vapors, can interfere with breathalyzer results. If you believe that environmental factors may have affected your test, it is essential to gather evidence to support this claim.

Challenging the Accuracy of Blood Test Results

While blood tests are generally considered more accurate than breathalyzer tests, they are not immune to errors. Some ways to challenge the accuracy of a blood test in a DUI case include:

  • Investigating the chain of custody: The blood sample must be properly collected, stored, and transported to the lab to ensure accurate results. If there is any break in the chain of custody, the test results may be inadmissible.
  • Questioning the lab's procedures: The lab that analyzes the blood sample must follow strict protocols to ensure accurate results. If the lab made any errors in processing the sample or interpreting the results, the evidence may be inadmissible.
  • Considering the time elapsed since drinking: The amount of alcohol in your system can change over time, and it is possible that your BAC was below the legal limit at the time of driving. If you can prove that enough time had elapsed between drinking and the blood test, the results may be challenged.

Seeking Professional Help

Challenging breathalyzer and blood test results in a DUI case can be a complex process that requires a thorough understanding of the law and scientific principles. If you are facing a DUI charge, it is essential to seek the help of an experienced Miami DUI defense attorney like Law Office of Michael Mirer, P.A. to help you navigate this process and build a strong defense. With our insight in DUI cases, we can help you challenge the accuracy of your breathalyzer or blood test results and fight for the best possible outcome in your case.