Drug-related DWI charges in Texas carry serious consequences that extend far beyond what many people expect. Whether you’ve taken prescribed medication, over-the-counter drugs, or illegal substances, Texas law treats all drug impairment the same as alcohol when it comes to Driving While Intoxicated (DWI) charges.
Because these cases are often complex and highly technical, working with an experienced Dallas DWI Defense Lawyer is critical to protecting your rights.
The experienced attorneys at the Law Offices of Richard C. McConathy have successfully defended clients throughout North Texas in complex drug-related DWI cases involving prescription medications, illegal drugs, and blood test challenges.
What Is a Drug-Related DWI in Texas?
Under Texas Penal Code Section 49.04, a drug-related DWI occurs when a person operates a motor vehicle in a public place while intoxicated by drugs. Unlike alcohol DWI cases that have a specific blood alcohol concentration (BAC) threshold of 0.08%, there is no specific legal limit for drugs in Texas. Instead, the law focuses on impairment of your normal mental or physical faculties.
You can be charged with DWI even if the drug was legally obtained or prescribed by a doctor, if it impairs your driving ability. Having a valid prescription is not an automatic defense to drug-related DWI charges.
Proposed Legal Changes in Texas (2025)
Texas lawmakers are considering stricter DWI penalties through Senate Bill 2320, which would take effect September 1, 2025, if passed:
- First-time DWI would be upgraded from Class B to Class A misdemeanor
- DWI with BAC of 0.15+ would become a state jail felony
- Second DWI offenses would become state jail felonies
Important: These changes have not been enacted yet and are still pending in the legislature.
Types of Drugs That Can Lead to DWI Charges
Illegal Drugs
Texas law treats all illegal substances equally when it comes to DWI charges. The most common cases involve marijuana, cocaine, methamphetamines, and synthetic drugs like K2/Spice.
Prescription Medications
Prescription drug DWI cases are increasingly common and often surprise defendants who believed they were legally taking their medication. Common medications that lead to DWI charges include:
| Medication Type | Common Drugs | Impairing Effects |
|---|---|---|
| Benzodiazepines | Xanax, Valium, Ativan | Drowsiness, slow reflexes, confusion |
| Sleep Aids | Ambien, Lunesta | Delayed reaction times, memory issues |
| Pain Medications | Oxycodone, Hydrocodone | Altered perception, drowsiness |
| Muscle Relaxants | Soma, Flexeril | Impaired coordination, dizziness |
For detailed information about prescription drug cases, see our guide on prescription drug DWI.
Over-the-Counter Medications
Even common over-the-counter medications can lead to DWI charges when taken in excessive doses, combined with other substances, or used contrary to package directions. Common OTC drugs include cold medicines containing diphenhydramine (Benadryl), cough syrups with dextromethorphan, and motion sickness medications.
How Police Detect Drug Impairment
Field Sobriety Tests and Their Limitations
Police officers use Standardized Field Sobriety Tests (SFSTs) as their primary tool for detecting drug impairment. However, these tests have significant limitations as they were originally created to detect alcohol impairment, not drug impairment. Medical conditions, environmental factors, and inadequate officer training can all affect test performance.
Drug Recognition Experts (DREs) and Their Process
A drug recognition expert (DRE) is a police officer trained to recognize impairment in drivers under the influence of drugs. DRE candidates must complete extensive training including a minimum of 12 drug evaluations under supervision and obtain a minimum 75% toxicological corroboration rate.
The 12-Step DRE Evaluation includes:
- Breath alcohol test review
- Interview with arresting officer
- Preliminary examination
- Eye examinations
- Divided attention psychophysical tests
- Vital signs examination
- Dark room examinations
- Examination for muscle rigidity
- Examination for injection sites
- Interrogation of the suspect
- Forming an opinion
- Toxicological examination
Important: You are not required by law to submit to the DRE tests. The No Refusal Weekend does not apply to the field sobriety or DRE testing (It only applies to chemical tests).
Blood/Urine Testing and Admissibility
Unlike breath tests for alcohol, drug detection requires blood or urine testing. These tests present unique challenges including detection vs. impairment issues (drugs can remain detectable long after effects wear off), false positives from cross-reactivity with legal medications, and chain of custody requirements.
Refusal of Tests and Legal Implications
Texas has an “implied consent” law, meaning that by driving in Texas, you’ve agreed to chemical testing if arrested for DWI. Refusing a breath or blood test has serious consequences including automatic license suspension up to 1 year for first refusal and enhanced penalties that can be used against you in court. Officers can also obtain a warrant to draw your blood forcibly in many circumstances.
Penalties for Drug-Related DWI in Texas
First-Time Offenders
The penalties for a drug-related DWI in Texas are generally comparable to those for alcohol-related DWIs. For first-time offenders:
First-Time Offenders (Class B Misdemeanor):
- Fines: Up to $2,000
- Jail time: 72 hours to 180 days
- License suspension: 90 days to 1 year
- State surcharge: $3,000-$6,000 over three years
Repeat Offenders
Second Offense (Class A Misdemeanor): Up to a $4,000 fine, one month to one year in jail, and a driver’s license suspension of 180 days to two years
Third Offense (Third Degree Felony): Up to a $10,000 fine, two to ten years in prison, and a driver’s license suspension of 180 days to two years
Enhanced Penalties
With High BAC (0.15 or higher): A DWI with a blood alcohol concentration of 0.15 or higher will now be a state jail felony (instead of a Class A misdemeanor) starting September 1, 2025.
With Child Passenger: You will be charged with child endangerment if you’re driving impaired with children under 15.
| Offense Level | Classification | Fine | Jail/Prison | License Suspension |
|---|---|---|---|---|
| First | Class B Misdemeanor | Up to $2,000 | 72 hours – 180 days | 90 days – 1 year |
| Second | Class A Misdemeanor | Up to $4,000 | 30 days – 1 year | 180 days – 2 years |
| Third | 3rd Degree Felony | Up to $10,000 | 2 – 10 years | 180 days – 2 years |
Common Defenses Against Drug DWI Charges
Challenging Test Results
Drug test results can be challenged on multiple grounds including false positives (many legal medications can cause false positive results), contaminated samples due to chain of custody issues, and laboratory errors from testing facilities failing to maintain strict protocols.
Contesting Officer Observations and DRE Findings
Officer testimony about impairment signs can be challenged by medical explanations for symptoms, environmental factors affecting test performance, training deficiencies, and DRE protocol violations.
Lack of Probable Cause
Every DWI stop must be supported by reasonable suspicion. We challenge stops based on minor traffic violations insufficient to justify extended detention, anonymous tips without corroborating evidence, and pretextual stops targeting specific demographics.
No Valid Prescription Defense
Under Texas Penal Code Section 49.10, having a valid prescription is explicitly not a defense to drug DWI charges. The statute clearly states: “the fact that the defendant is or has been entitled to use the alcohol, controlled substance, drug, dangerous drug, or other substance is not a defense.”
However, prescription information can still be relevant for:
- Mitigating circumstances: Showing responsible medication use for sentencing
- Challenging impairment: Demonstrating therapeutic rather than impairing levels
- Alternative explanations: Medical conditions that mimic impairment symptoms
Related Offenses Often Charged Alongside Drug DWI
Drug-related DWI arrests often result in additional charges including possession of controlled substances, possession of marijuana, open container violations, and resisting arrest charges.
DUI vs. DWI in Texas – What’s the Difference?
In Texas, the terms are often used interchangeably, but there are important distinctions:
DWI (Driving While Intoxicated):
- Primary charge for adults (21+)
- Applies to both alcohol and drugs
- More serious penalties
DUI (Driving Under the Influence):
- Primarily used for minors (under 21)
- Zero tolerance: Any detectable amount of alcohol
- Can also apply to any age for drug-related offenses in some contexts
For drivers that are under 21, Texas has a “zero tolerance” policy. This means any detectable alcohol in the blood system can lead to charges.
What to Do If You’re Arrested for Drug-Related DWI
Remain Silent and Request a Lawyer
Your Fifth Amendment rights are crucial in drug DWI cases. Avoid admitting to taking any medications or substances, describing symptoms you’re experiencing, or providing detailed medical history to officers. Anything you say will be used against you in court.
Document All Details of the Arrest
If possible, mentally note the time and location of stop, officer’s stated reason for the stop, weather and road conditions, your physical condition and any medical issues, and witnesses present.
Avoid Discussing Medications Without Legal Counsel
Police may ask about prescriptions during arrest. While you must provide identification, you don’t have to list all medications you’re taking, explain dosages or timing, or discuss medical conditions.
Call a Texas Drug DWI Defense Attorney Immediately
Time is critical in drug DWI cases. You have only 15 days to request an Administrative License Revocation (ALR) hearing to contest license suspension.
Our attorneys provide immediate assistance with ALR hearing requests, bond arrangements, evidence preservation, and witness identification.
Why Choose Our Texas DWI Lawyers?
Proven Track Record with Drug-Related Cases
The Law Offices of Richard C. McConathy has successfully defended hundreds of drug-related DWI cases. Our success comes from understanding both the legal and scientific aspects of drug DWI cases, including the complex interplay between prescription medications, illegal substances, and Texas DWI law.
Local Court Experience
Richard C. McConathy has over 35 years of experience defending clients in Dallas, Tarrant, Collin, and surrounding counties. This local experience provides advantages including familiarity with local judges and prosecutors, knowledge of court-specific procedures, and established relationships that can benefit negotiations.
Comprehensive Defense Strategy
Our approach to drug DWI cases includes thorough case investigation with independent testing of evidence and expert witness consultation, legal challenge preparation including motion practice for evidence suppression, and scientific evidence analysis with blood/urine test reliability assessment.
For experienced representation in your drug-related DWI case, contact our Dallas DWI lawyer today.
Frequently Asked Questions (FAQ)
Can I get a DWI for taking prescription drugs in Texas?
Yes, you can be charged with DWI even if the drug was legally obtained, prescribed by a doctor, or an over-the-counter medication, if it impairs your driving ability. The fact that you have a prescription is not an affirmative defense.
What is the penalty for a drug-related DWI in Texas?
The penalties for a drug-related DWI in Texas are generally comparable to those for alcohol-related DWIs. Starting September 1, 2025, first-time offenders face Class A misdemeanor charges with potential fines up to $3,500 and 72 hours to 1 year in jail.
Will I lose my license after a DWI involving drugs?
Yes, drug-related DWI convictions result in driver’s license suspension ranging from 90 days to 2 years, depending on the offense level and any prior convictions.
Do DWI charges differ for marijuana vs Xanax?
Under Texas law, the charge is the same regardless of the drug type. However, prosecution strategies and available defenses may differ based on whether the substance was illegal drugs like marijuana or prescription medications like Xanax.
What does a drug recognition expert do?
The DRE protocol is a standardized and systematic method of examining a Driving Under the Influence of Drugs (DUID) suspect to determine: (1) Whether the suspect is impaired; and if so; (2) Whether the impairment relates to drugs or a medical condition; and if drugs; (3) The category or combination of categories of drugs that is the likely cause of the impairment.