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Blood Testing and How to Refute Blood Evidence in Colorado

Blood testing plays a crucial role in determining an individual’s level of intoxication during DUI (Driving Under the Influence) cases. Law enforcement officers often rely on blood tests as a reliable method to measure an individual’s Blood Alcohol Content (BAC), a key factor in DUI arrests. In this article, we will explore the blood testing process, its reliability, and the legal options available to individuals facing DUI charges based on blood test results.

The Blood Testing Process: A Closer Look

When law enforcement suspects a driver of being under the influence, they may opt for a blood test to assess the driver’s BAC accurately. The blood testing process typically involves transporting the alleged drunk driver to a hospital, fire department, ambulance, or another location where a certified phlebotomist is available. The phlebotomist’s role is crucial in collecting blood samples that will be used as evidence in a DUI case.

A blood kit containing two blood sample tubes is used for the collection. One sample is designated for the prosecutor’s use. At the same time, the other is reserved for the alleged drunk driver’s independent verification of the results. It is important to note that individuals can have their blood independently tested by their chosen laboratory to challenge the prosecutor’s results. This independent verification can be a valuable tool to prove innocence following a blood draw.

Challenging Blood Test Results

While phlebotomists are generally skilled professionals, mistakes can occur during blood testing. These errors could potentially influence the outcome of a DUI case. Suppose blood test results are found to be inaccurate or elevated. In that case, legal avenues may be pursued to challenge the test results. Some common grounds for contesting blood test results include:

  1. Use of an Uncertified Blood Kit: If an uncertified blood kit was utilized, it may raise questions about the accuracy and reliability of the results.
  1. Improper Blood Storage: Proper storage procedures are essential to maintain the integrity of blood samples. Any deviation from these procedures could lead to contamination or inaccurate results.
  1. Tester’s Qualifications: Ensuring that the phlebotomist performing the blood draw is properly trained in chemistry and toxicology is crucial for accurate results.
  1. Data Interpretation Errors: Misinterpretation of data can lead to incorrect conclusions about an individual’s BAC level.
  2. Contamination: Contamination of the blood sample during collection or processing can significantly impact the accuracy of the results.
  1. Mix-Up of Samples: There is a possibility that blood samples from different DUI suspects may be mixed up, leading to inaccurate test results.
  1. Protocol Violations: If proper protocol was not followed during the blood collection process, it may provide grounds for challenging the results.

Understanding the intricacies of DUI laws, especially regarding blood testing, can be complex for individuals facing DUI charges. Therefore, seeking independent verification of blood test results and consulting with an experienced DUI lawyer is critical.


Blood testing remains a fundamental tool in assessing BAC levels during DUI cases. While generally reliable, mistakes can happen during the blood testing process. Independent verification of blood test results and legal counsel are essential steps for individuals facing DUI charges based on blood test evidence. At Thomas & Ahnell, LLC, we specialize in alcohol and drug-related driving offenses in Colorado and can provide expert guidance and representation to those navigating the complexities of DUI cases, including challenging blood test results when necessary. Your rights and freedom are our top priority.

Do you have further questions or concerns? Call us or contact the attorneys at Thomas & Ahnell, LLC, and we will be happy to help.

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