Blood vs Breath Tests in Texas DWI Cases: Which Is Easier to Challenge?

 Facing a DWI charge in Galveston can be overwhelming, and the stakes are high. From fines and probation to potential jail time, a DWI conviction can have long-term consequences on your life. At Zendeh Del & Associates PLLC, we understand the complexity of Texas DWI laws and the importance of challenging every piece of evidence against our clients, including chemical tests like breath and blood tests. These tests are often decisive in proving intoxication, but they are not infallible. The differences between them, the procedures involved, and the potential for errors create opportunities for a skilled attorney to contest their accuracy and reliability in court. Understanding these nuances can be critical in building a strong defense strategy.

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Chemical Testing in Texas DWI Cases

Texas law authorizes law enforcement officers to conduct chemical tests to determine a driver’s blood alcohol concentration (BAC) if they suspect intoxication. The two primary tests are breath tests, often administered on the scene or at a police facility, and blood tests, which require a medical professional to draw and analyze a sample in a certified laboratory. Each method carries unique procedures and legal implications. Breath tests are convenient, immediate, and widely used, while blood tests are considered more precise but involve more complex handling and documentation. Despite the apparent accuracy of these tests, both can be challenged based on procedural errors, device calibration issues, or chain-of-custody problems.

Breath Tests: Convenience Versus Vulnerability

Breath tests, commonly known as breathalyzers, provide law enforcement with rapid BAC results. While their convenience makes them widely used, several factors can impact their reliability. Calibration and maintenance of the device are critical. A breathalyzer that is improperly calibrated or maintained can produce inaccurate readings, and these errors are often grounds for challenge. The officer administering the test must follow strict protocols, including observing the subject for a specific period prior to the test, ensuring no mouth alcohol is present, and properly recording results. Any deviation from these procedures can be scrutinized in court. Additionally, physiological factors, such as medical conditions, body temperature, or even recent consumption of certain foods or mouthwash, can skew results. Given these variables, breath tests can often be contested more successfully than blood tests if any procedural or mechanical missteps occurred.

The Zendeh Del & Associates, PLLC Team

Jonathan Zendeh Del

Trial Attorney

Gabe Perez

Trial Attorney

Carolyn Zendeh Del

Certified Mediator, Attorney

Chase Waterwall

Trial Attorney

Dorothy Porretto

Office Manager, Paralegal

Pedro Ruiz

Judge

Zaira Banda

Legal Assistant

Colleen Herndon

Legal Assistant

Blood Tests: Precision and Scrutiny

Blood tests are generally regarded as more accurate due to their direct measurement of BAC. However, these tests are not immune to challenges. The chain of custody is a central concern in Texas courts. Every step, from sample collection to laboratory analysis, must be thoroughly documented and secure. Any gaps in documentation can render the results inadmissible. Laboratory errors, including mislabeling, contamination, or improper storage, are also grounds for challenging the evidence. Medical conditions or medications that influence alcohol absorption can further complicate the interpretation of blood test results. While blood tests may appear more reliable, a thorough review by a Galveston DWI attorney can uncover vulnerabilities that could be decisive during litigation.

Comparing the Challenges of Blood and Breath Tests

Deciding which type of test is easier to challenge depends on the specific circumstances of the case. Breath tests often contain more procedural pitfalls because they rely heavily on correct device operation and adherence to pre-test observation rules. Blood tests, while technically more precise, present opportunities for challenge primarily through errors in handling, documentation, or laboratory analysis. A skilled DWI defense attorney evaluates the evidence carefully, identifies potential weaknesses in testing protocols, and strategically challenges the results to protect the client’s rights. In practice, breath tests are often targeted first because errors are more common and more easily documented. However, a blood test with chain-of-custody lapses or lab mistakes can also be effectively contested.

Legal Framework for DWI Testing in Texas

Texas law requires that all chemical tests be administered in accordance with strict procedural and statutory guidelines. Under the implied consent law, drivers suspected of DWI must submit to a chemical test upon request. Refusing a test can result in an automatic license suspension. However, the law also establishes the standards for proper administration, certification of devices, and chain-of-custody documentation. Evidence collected in violation of these standards can be excluded from court proceedings, making procedural scrutiny critical. Understanding these rules is essential for mounting an effective defense, and Zendeh Del & Associates PLLC has extensive experience in identifying these nuances and using them to challenge unreliable evidence.

Case Results

$11,820,000

WARN ACT
SETTLEMENT

Reached a settlement of $11,820,000

$11,820,000

WARN ACT CASE
SETTLEMENT

Employees fired when not given proper notice

Not Guilty

DRUG JURY TRIAL

Client was a dentist caught with 12 grams of methamphetamine. 

Case Dismissed

DRAM SHOP CASE

Death of a person who was run over by a drunk person who left a party.

$2,500,000

CAR ACCIDENT

Confidential settlement of $2,500,000

$4,500,000

DRAM SHOP CASE

Death of a person who was run over by a drunk person who left a party

Not Guilty

DWI JURY TRIAL

Client was asleep on the side of the road with the car on. Breath was .248

Case Dismissed

STATE OF TEXAS v. C.S.

Wrecked motorcycle while leaving the beach, an officer witnessed the accident and assumed he was intoxicated

Practical Strategies for Contesting Tests

When building a defense, attorneys often focus on multiple angles. For breath tests, this may include reviewing calibration and maintenance records, analyzing whether the officer followed observation procedures, and evaluating physiological factors that may have influenced the reading. For blood tests, a meticulous audit of the chain of custody, documentation of lab protocols, and examination of storage and handling practices can reveal errors. Both tests require an attorney to scrutinize every step from collection to presentation in court. By identifying flaws, the defense can seek exclusion of unreliable results or reduce the weight the court assigns to them.

Case Scenarios in Galveston DWI Defense

Numerous cases in Galveston demonstrate how these challenges play out. Breath test readings have been successfully contested when officers failed to properly observe the subject prior to testing or when maintenance logs revealed calibration issues. Blood tests have been challenged effectively when chain-of-custody breaks or lab procedural errors were documented. Each case is unique, and a skilled DWI attorney assesses the evidence in context, examining both procedural compliance and scientific validity to develop a tailored defense strategy.

The Importance of Early Legal Intervention

Timely engagement with an experienced attorney can make a significant difference. Early review of evidence allows for immediate action, whether that involves requesting laboratory records, inspecting device logs, or preparing expert testimony. In Galveston, where DWI charges carry serious consequences, retaining Zendeh Del & Associates PLLC early ensures that all potential challenges to chemical testing are thoroughly explored and leveraged to protect the client’s driving privileges and overall case outcome. Breath and blood tests are critical elements in DWI prosecutions, but neither is infallible. Both contain vulnerabilities that can be challenged with the right legal strategy. Breath tests, due to procedural sensitivities, often offer more immediate avenues for challenge, while blood tests require meticulous review of chain-of-custody and lab protocols. Effective defense in Galveston requires a combination of procedural knowledge, scientific understanding, and courtroom experience. Zendeh Del & Associates PLLC provides comprehensive support, analyzing every aspect of the testing process to ensure that defendants receive a fair evaluation of their case. By identifying weaknesses in chemical testing, they can protect rights, preserve driving privileges, and strive for the most favorable outcome possible.

To learn more about this subject click here: How to Prepare for a Court Appearance in a DWI Case in Galveston