Challenging Blood Test Results in DUI Cases

As a DUI defense attorney in Tucson, Arizona, I understand how overwhelming a DUI charge can feel. The stakes are high, and the process is intimidating. One common element in DUI cases is the blood test, often presented as indisputable proof of impairment. However, as a skilled criminal defense attorney, I know that blood test results are far from infallible. Errors can occur at various stages of testing, and understanding these vulnerabilities is crucial for building a strong defense.

At AJB Law Firm, we have expertise in criminal defense and DUI defense, focusing on challenging the evidence against our clients. If you or someone you know is facing a DUI charge in Tucson, Arizona, this post will help you understand how blood test results can be scrutinized and challenged in court.

Why Blood Tests Are a Key Issue in DUI Cases

Blood tests are often seen as the "gold standard" in determining blood alcohol concentration (BAC) or the presence of drugs in DUI cases. Unlike breath tests, which estimate BAC indirectly, blood tests measure alcohol or drugs directly in the bloodstream. While this method is more accurate, it is not foolproof. Problems in collection, storage, and analysis can lead to incorrect results, making it vital to examine the process critically. For anyone charged with DUI, understanding how blood tests work and where they might fail is a critical part of mounting a defense.

Improper Collection Practices

The process of collecting blood samples is highly regulated, but even small deviations from protocol can compromise the results. For instance, if an alcohol-based swab is used to clean the site of the blood draw, it can introduce ethanol into the sample, artificially inflating BAC levels. Mislabeling or failing to properly seal the sample can also lead to mix-ups or tampering, which casts doubt on the reliability of the results.

Chain of custody is another critical issue. Every person handling the blood sample must document their actions. If the chain of custody records are incomplete or missing, it becomes difficult to prove that the sample was not contaminated or altered. An experienced DUI defense attorney will closely scrutinize these records for any inconsistencies.

Storage Problems

After the blood sample is collected, it must be stored under specific conditions to maintain its integrity. Improper refrigeration is a common problem. If a sample is not kept at the correct temperature, it can degrade, leading to inaccurate readings. Additionally, without proper preservatives, blood samples can ferment, creating ethanol and artificially increasing the reported BAC levels.

These issues are not merely technicalities. They go to the heart of whether the blood test results are reliable. A defense attorney will review storage logs and interview lab personnel to uncover any mishandling that could compromise the evidence.

Analytical Errors

The analysis of blood samples is typically performed using Gas Chromatography (GC), a highly sensitive technique designed to detect and quantify substances in the blood. However, even this sophisticated method is not immune to error. Calibration issues are one potential problem. The Gas Chromatograph must be carefully calibrated before each use, and any deviation from this process can result in unreliable readings.

Contamination within the lab is another concern. If the equipment is not properly cleaned between tests, residual substances from previous samples can carry over and contaminate subsequent results. Furthermore, if the GC method used was not properly validated for forensic purposes, the test results may not meet the standards required for evidence in a criminal case.

Human Error

Even with advanced technology, human error remains a significant factor in blood testing. Clerical mistakes, such as mislabeling samples or entering data incorrectly, can have serious consequences. These errors can lead to mismatched samples or incorrect results being reported in court.

Additionally, the qualifications and training of the analysts performing the tests are critical. Analysts who lack proper training or experience may mishandle samples or misinterpret the data. In some cases, analysts may be influenced by confirmation bias, interpreting results in a way that aligns with the prosecution’s narrative. A skilled defense attorney will explore these potential vulnerabilities through depositions and cross-examinations.

Legal and Procedural Challenges

Forensic labs must adhere to strict protocols to ensure the accuracy and reliability of their results. Deviations from these protocols can provide grounds to challenge the evidence. For example, if the lab conducting the tests is not accredited, its practices may not meet accepted standards for forensic analysis. Similarly, a failure to run quality control samples alongside the test samples can cast doubt on the validity of the results.

When these lapses occur, the defense can file motions to suppress the blood test results or argue that they should be excluded from evidence. These motions are based on the principle that unreliable evidence should not be used to convict a defendant.

How a DUI Defense Attorney Can Challenge Blood Test Results

Challenging blood test results requires a detailed and methodical approach. The first step is to obtain and review all discovery materials related to the blood test. This includes lab reports, chain of custody records, calibration logs, and analyst certifications. Every detail is scrutinized for inconsistencies or errors.

Engaging a forensic toxicologist as an expert witness can also be invaluable. These experts can provide an independent analysis of the blood test results and identify flaws in the prosecution’s evidence. Their testimony can help explain complex scientific issues to the court and provide alternative explanations for elevated BAC levels.

Cross-examining the prosecution’s witnesses is another critical strategy. By questioning the forensic analyst about their methods, training, and adherence to protocols, a defense attorney can expose weaknesses in the case. For example, the attorney might ask about potential contamination, improper calibration, or lapses in quality control.

The Role of a Tucson DUI Defense Attorney

As a DUI defense attorney in Tucson, Arizona, I am committed to protecting my clients’ rights and ensuring that the evidence against them is thoroughly scrutinized. At AJB Law Firm, we have the experience and resources to identify procedural errors and scientific flaws in blood testing, work with leading forensic experts to build a strong defense, and challenge the prosecution’s case at every stage.

Facing a DUI charge is stressful, but you don’t have to navigate it alone. With a dedicated Tucson criminal defense attorney by your side, you can fight for the best possible outcome. At AJB Law Firm, we specialize in DUI defense and are here to help.

Contact Amanda Bynum at AJB Law Firm

If you or a loved one is facing a DUI charge in Tucson, Arizona, don’t wait. Contact AJB Law Firm to schedule a consultation. With extensive experience in criminal defense and DUI defense, I am here to provide the aggressive representation you deserve.