DWI Tests
Almost every DWI case in Texas comes down to one thing: the tests. A breath machine, a vial of blood, or a set of roadside balancing exercises, the State treats these as hard proof you were intoxicated. They are not. Every one of these tests depends on equipment that fails, procedures that get skipped, and human judgment that’s often wrong. Understanding how they work, and how they break, is the heart of a strong DWI defense.
There are three kinds of tests you may face after a Houston DWI stop, and each can be challenged:
Breath tests. In Texas, breath samples are analyzed by the Intoxilyzer 9000. It assumes your body chemistry matches a population average, it can be thrown off by mouth alcohol and medical conditions, and Texas runs it without a key quality-control feature that’s built into the machine. Learn how we fight breath tests →
Blood tests. A blood draw sounds definitive, but it depends on a proper warrant, a qualified person drawing the blood, correct storage, and an error-free crime lab, and Texas labs have a documented history of problems. Learn how we fight blood tests →
Field sobriety tests. The roadside “tests”, following a pen with your eyes, walking a line, standing on one leg, are subjective, affected by your age, weight, footwear, medical conditions, and the officer’s own scoring. You can refuse them in Texas. Learn how we fight field sobriety tests →
Why the tests matter more than almost anything else
Prosecutors build DWI cases on test results because juries find numbers persuasive. But a number is only as reliable as the process behind it. When a Houston DWI lawyer digs into the maintenance logs, the officer’s certification, the 15-minute observation period, the blood-draw warrant, or the way a field sobriety test was scored, results that looked airtight often fall apart, and when the test evidence is suppressed or discredited, the case frequently collapses with it.
At Blass Law, Jay Blass Cohen has spent his entire career defending people accused of DWI in Houston and Harris County. Not prosecuting them. We know how these tests are supposed to be administered, where officers and labs cut corners, and how to turn the State’s “proof” into reasonable doubt.
Arrested for DWI in Houston? Call Blass Law at (713) 664-4000 for a free, confidential case evaluation: and remember your 15-day ALR deadline to protect your license.
(Related: how much a DWI costs in Houston · first-offense DWI)
Related DWI Test Defense Guides
Reviewed by Jay Blass Cohen, founder of Blass Law PLLC, ACS-CHAL Forensic Lawyer-Scientist, certified Drug Recognition Expert, and SFST instructor, serving Houston since 2009. This article is general information, not legal advice for your situation. Prior results do not guarantee a similar outcome.