Drug-Related DUI (DUID) Defense in San Antonio: Protecting Your Rights Against Prescription and Illegal Drug Charges

In San Antonio and across Texas, a Driving While Intoxicated (DWI) charge is not limited to alcohol. If you are accused of operating a vehicle under the influence of prescription medications, over-the-counter drugs, or controlled substances, you are facing a Drug-Related DUI, often called DUID (Driving Under the Influence of Drugs). These charges are uniquely complex and carry the same severe penalties as an alcohol-related DWI, yet the evidence against you is far more subjective and scientifically nuanced.

At Barton & Associates, our San Antonio criminal defense attorneys possess the specialized knowledge required to defend against these serious allegations. We understand that a legal prescription does not make you immune to arrest, and we know how to challenge the state’s often-flawed methods of proving drug impairment. Your driver’s license, your freedom, and your future require an aggressive, science-based defense strategy from the very beginning.

Understanding Texas DUID Law: It’s Not Just About Illegal Drugs

Under Texas Penal Code § 49.04, a DWI occurs when a person is intoxicated while operating a motor vehicle in a public place. “Intoxicated” is legally defined in two ways: not having the normal use of mental or physical faculties due to any substance, OR having a blood alcohol concentration (BAC) of 0.08% or more.

The critical distinction in a DUID case is that there is no per-se legal limit for drugs in your system (with the specific exception of marijuana, discussed below). The prosecution cannot simply point to a number on a test result to prove guilt. Instead, they must convince a judge or jury that a substance—whether legally prescribed or not—caused you to lose your “normal use” of faculties. This makes the state’s case inherently subjective and vulnerable to a skilled defense.

Common substances involved in DUID arrests in San Antonio include:

• Prescription Medications: Benzodiazepines (Xanax, Valium), opioids (hydrocodone, oxycodone), sleep aids (Ambien), muscle relaxants, and certain antidepressants or stimulants.
• Over-the-Counter (OTC) Drugs: Medications containing diphenhydramine (e.g., Benadryl, sleep aids) or dextromethorphan (e.g., NyQuil, cough syrup) can cause drowsiness or dizziness.
• Controlled Substances: Marijuana, cocaine, methamphetamine, MDMA, and psychedelics.
• Combinations: Mixing any of the above, or combining drugs with even a small amount of alcohol.

Important Note on Marijuana (Cannabis): Texas has established a specific, per-se limit for THC. If a blood test reveals 1 nanogram or more of active THC per milliliter in your system, the state can use that as primary evidence of intoxication, shifting the burden to you. This makes marijuana DUID cases particularly challenging and requires an immediate, sophisticated legal response.

The Severe Penalties for a DUID Conviction in Texas

The penalties for a Drug-Related DUI are identical to those for an alcohol-related DWI and escalate dramatically with each offense. The court makes no distinction between a substance that was legally prescribed and one that was illegally obtained.

• First Offense DUID: A Class B misdemeanor punishable by up to 180 days in jail, a fine of up to $2,000, and a driver’s license suspension from 90 days to one year. You will also face an annual surcharge of $1,000 to $2,000 for three years to retain your license after suspension.
• Second Offense DUID: A Class A misdemeanor punishable by up to one year in jail, a fine of up to $4,000, and a license suspension for up to two years.
• Third Offense DUID: A third-degree felony punishable by 2 to 10 years in a state prison, a fine of up to $10,000, and a license suspension for up to two years.

Furthermore, a DUID conviction carries all the same collateral consequences as an alcohol DWI: a permanent criminal record that hinders employment and housing, skyrocketing insurance premiums, loss of professional licenses, and profound personal and social stigma.

The Critical 15-Day Deadline: Your ALR Hearing for a DUID Arrest

Just like an alcohol DWI, a DUID arrest triggers the Administrative License Revocation (ALR) process. The arresting officer will confiscate your Texas driver’s license and issue a temporary permit. From the date of your arrest, you have only 15 calendar days to formally request an ALR hearing to fight the automatic suspension of your license.

If you miss this absolute deadline, your license will be suspended 40 days after your arrest, regardless of the status of your criminal case. For DUID arrests, this hearing is a vital strategic opportunity. Our attorneys at Barton & Associates file this request immediately to:

• Cross-examine the arresting officer under oath about his observations and procedures long before the criminal trial.
• Gain early discovery into the evidence the state intends to use.
• Preserve testimony that may reveal inconsistencies or procedural errors.
• Potentially save your driving privileges at the outset.

Our Science-Based Defense Strategy for San Antonio DUID Cases

Defending against drug-related DUI charges requires a fundamentally different approach than alcohol cases. At Barton & Associates, we deploy a multi-layered defense focused on the inherent weaknesses in the state’s evidence.

1. Challenging the Traffic Stop and Arrest Probable Cause

The foundation of every DUID case is the officer’s initial justification. We meticulously scrutinize the reason for the traffic stop. Was there a valid traffic violation, or was it a pretextual stop? Furthermore, we attack the officer’s basis for the arrest. “Slurred speech” and “poor balance” can be caused by fatigue, medical conditions, or even the stress of the traffic stop itself. Without clear evidence of alcohol (odor, admission), the officer’s claim of “drug impairment” is often a speculative guess that we can challenge as insufficient for probable cause.

2. Deconstructing the “Drug Recognition Expert” (DRE) Evaluation

In many DUID cases, the police will call in a specially trained officer known as a Drug Recognition Expert (DRE). The DRE conducts a 12-step protocol, including pulse checks, eye examinations, and muscle tone tests, to supposedly identify the category of drug impairing a driver. While presented as scientific, the DRE protocol is highly subjective and its conclusions are frequently disputed in the scientific community. Our defense strategy includes:

• Challenging the DRE officer’s training, certification records, and adherence to strict protocol.
• Hiring independent medical and toxicology experts to testify that the observed signs are consistent with medical conditions (e.g., diabetes, neurological disorders), fatigue, or simply nervousness.
• Arguing that the DRE’s opinion is an unreliable pseudoscience, not admissible under Texas evidence rules (a Daubert challenge).

3. Aggressively Challenging the Blood Test Evidence

In DUID cases, a blood test is the prosecution’s primary piece of “hard” evidence. However, from the moment the needle pierces the skin, the evidence is vulnerable. Our defense, often in collaboration with retained forensic toxicologists, attacks every stage:

• Chain of Custody: We demand logs to prove your blood sample was not mislabeled, swapped, or left unsecured.
• Blood Draw Procedures: Was the draw conducted in a sanitary manner by a qualified phlebotomist? Was the correct preservative (and no other chemicals) in the vial?
• Laboratory Analysis: The lab must use Gas Chromatography-Mass Spectrometry (GC-MS) for confirmation. We subpoena the lab’s proficiency testing records, calibration logs, and standard operating procedures to find errors. Even a minute deviation can invalidate the result.
• Metabolites vs. Active Drug: A test may only detect inactive drug metabolites that remain in your system for days or weeks after any impairing effects have worn off. We fight to exclude this irrelevant and prejudicial evidence.
• Warrant Validity: If your blood was drawn pursuant to a warrant, we analyze the affidavit for factual inaccuracies or omissions that would render the warrant invalid, making the blood test result inadmissible.

4. Presenting Alternative Explanations and Affirmative Defenses

A powerful DUID defense proactively offers a legitimate reason for the client’s condition or the test results.

• Valid Medical Prescription: We work with your doctor to establish that you were taking medication as directed and had no reason to believe it would impair your driving. This does not automatically exonerate you, but it is crucial for jury sympathy and can defeat allegations of “illegal” drug use.
• “Involuntary Intoxication” Defense: If a medication had an unexpected, severe side effect that you could not have anticipated, this may provide a legal defense.
• Rising Blood Level Defense: For marijuana or certain prescriptions, we can argue that you were not impaired while driving, but the substance was still being absorbed into your bloodstream, leading to a higher test level later.

Why Barton & Associates Is Your Strongest Ally in a San Antonio DUID Case

Facing a DUID charge requires more than a general criminal lawyer; it demands an attorney who understands forensic toxicology, pharmacology, and the specific tactics of the Bexar County District Attorney’s Office.

• Mastery of DUI Science: We invest continuously in education on drug metabolism, toxicology testing, and the latest studies debunking field sobriety tests for drug impairment. We don’t just question the science; we understand it well enough to dismantle it in court.
• Former Prosecutorial Experience: Our team includes attorneys who have been on the other side. This insider knowledge allows us to anticipate the prosecution’s strategy, identify the weaknesses in their case early, and negotiate from a position of strength.
• Network of Expert Witnesses: We have established relationships with respected toxicologists, pharmacologists, and medical doctors who can provide the independent expert testimony necessary to counter the state’s claims.
• Trial-Ready Reputation: Prosecutors know we are fully prepared to take complex DUID cases to trial. This reputation for fearless litigation often leads to better plea offers or even case dismissals when the state realizes its evidence cannot withstand our scrutiny.

Take Immediate Action to Protect Your Future

A DUID arrest is an overwhelming experience, but your actions in the first days and weeks are critical. Do not speak to investigators about your medications or what you consumed. Do not plead guilty at your arraignment in the mistaken belief that a prescription is a get-out-of-jail-free card.

The 15-day ALR deadline is already ticking. The prosecution is already working with the crime lab. Your defense must begin now.

Contact Barton & Associates today for a confidential, free consultation. Our San Antonio drug-related DUI defense attorneys will review the details of your arrest and start building your powerful, science-backed defense immediately.

Complete our online contact form for a prompt response, or call our office directly at 210-500-0000. Your driver’s license, your reputation, and your freedom are worth fighting for.

Main Category: Criminal Defense
Practice Area Category: DWI & Intoxication
Barton & Associates, Attorneys at Law
115 Camaron St, San Antonio, TX 78205
Office: 210-500-0000