The Science of the Defense: Challenging Forensic Evidence
In Texas, a DWI case often hinges on a number—a Blood Alcohol Concentration (BAC) of 0.08 or higher. However, that number is only as reliable as the machine that produced it and the human who handled the sample. At Jones White Legal, we dismantle the State’s "scientific" narrative by exposing the biological and mechanical flaws inherent in breath and blood testing.
The Flaws of the Intoxilyzer 9000
The Intoxilyzer 9000 is the primary breath-testing instrument used in Harris, Fort Bend, Brazoria, and Chambers Counties. While marketed as infallible, it is susceptible to significant errors:
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The 15-Minute Observation Period: Texas law requires officers to observe a suspect for a continuous 15 minutes before a breath test. This is to ensure "mouth alcohol" (from a burp, hiccup, or acid reflux) does not contaminate the deep lung air sample. If an officer was filling out paperwork or looking away, the entire test result is scientifically compromised.
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Biological False Positives: Conditions like GERD (Acid Reflux), Diabetes (Ketosis), or even a high-protein diet can cause the machine to "detect" alcohol that isn't actually in your bloodstream. We cross-examine the machine's inability to distinguish between ethanol and the isopropyl alcohol or acetone naturally produced by your body
Blood Testing: The "Gold Standard" Under Scrutiny
Many believe blood tests are impossible to beat, but they are often the most vulnerable evidence in a DWI trial. We focus on two critical scientific areas:
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The Chain of Custody: From the moment blood is drawn in a sanitary environment (as required by Texas Transportation Code § 724.017) to its arrival at the DPS lab, every second must be documented. We look for "gaps" where samples sat in hot police cars or unrefrigerated lockboxes, which can cause fermentation—leading the blood to actually produce its own alcohol after it left your body.
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Gas Chromatography Errors: The lab uses a process called Gas Chromatography to measure BAC. We scrutinize the "raw data" (chromatograms). Were the machines properly calibrated? Did "carryover" from a previous high-BAC sample contaminate yours? If the lab's "blanks" show signs of contamination, your result cannot be trusted.
The "Rising BAC" Defense
Under Texas law, the State must prove you were intoxicated at the time of driving, not at the time of the test (which often happens an hour or more later).
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Because alcohol takes time to absorb into the system, it is scientifically possible that you were below 0.08 while behind the wheel, but your BAC "rose" during the commute to the station and the waiting period before the test. This is known as the Rising BAC Defense, and we use toxicological modeling to prove it.