Defending a Texas DWI Based on Drug Metabolites, Not Impairment

Attorney Answer

A positive drug test does not prove a Texas DWI. Because Texas has no per se limit for drugs, the State has to prove you had actually lost the normal use of your faculties while you were driving — not that something showed up in a sample afterward.

This is written into the definition. Under Tex. Penal Code sec. 49.01(2), "intoxicated" means either (A) not having the normal use of mental or physical faculties by reason of the introduction of alcohol, a controlled substance, a drug, a dangerous drug, a combination of two or more of those substances, or any other substance into the body, or (B) having an alcohol concentration of 0.08 or more. Read prong (B) closely: it is limited to alcohol concentration. There is no equivalent number for methamphetamine, for cannabis, or for any drug metabolite. So when the alleged intoxicant is a drug, the State cannot get there with a lab result alone — it must prove loss of normal faculties at the time of driving under prong (A) of Tex. Penal Code sec. 49.01(2), as the offense is defined in Tex. Penal Code sec. 49.04. The mere presence of a drug, or of its inactive metabolite, in a sample does not by itself establish that element.

That matters directly to what you have described. Metabolites can remain detectable long after any effect has worn off. If your use was days before the stop, the difference between an active drug and an inactive metabolite — and the quantity of each — is the heart of your defense. I want to be careful here: no Texas court decision is being cited to you for a metabolite-versus-impairment rule, and you should not tell anyone one exists. The point stands on the words of the statute, which is a firmer place to stand anyway.

What the State will build its case from instead is everything other than the lab: the reason for the stop, the officer's description of your driving, the field sobriety tests, the video, and anything you said. Those are what your lawyer attacks.

On your children — if they were not in the vehicle, then where they were at the time of use is not the DWI issue. Do not volunteer that history to anyone. It is far more likely to create a new problem than to solve this one.

You fired your attorney. The case does not pause for that, and a missed setting turns a defensible case into a warrant.

What you can do

1. Confirm your next court date today by calling the court coordinator. Do this before anything else. 2. Retain new counsel now, or if you cannot afford one, file a written request with the court for appointed counsel and ask the clerk to date-stamp your copy. 3. Have counsel obtain the full lab report — not the summary. You want to know whether the analyst identified the active drug or only an inactive metabolite, and what quantity was reported. 4. Have counsel obtain the blood-draw paperwork: the warrant or your written consent, the chain of custody, and the analyst's records. 5. Get the in-car and body-worn video. What the officer wrote and what the video shows are frequently different, and the video is the best evidence of whether you had normal use of your faculties. 6. Say nothing about drug use to anyone other than your lawyer — not to the officer, not to a pretrial officer, not on a jail phone, not in a text message.

⏱ Time limits apply. A Texas DWI arrest starts an administrative license-suspension case that runs on its own clock, roughly 15 days from the notice of suspension handed to you at arrest — the exact date is printed on that paper. This is the deadline people lose while they are waiting for a court date, and it cannot be reopened once it passes. It is a separate proceeding from the criminal charge, decided in a different forum on a different standard of proof. You can win one and lose the other on the very same stop.