Drug-Related DWI in Texas

Understanding DWI charges involving marijuana, prescription medications, and controlled substances beyond alcohol.

Drug DWI Legal Definition

No Minimum Level Required

Unlike alcohol DWI (0.08% BAC), there is no minimum amount of drugs required for a DWI conviction. Any detectable amount that impairs your abilities can result in charges.

Texas Penal Code 49.04
DWI by Drug Impairment:
  • Not having normal use of mental faculties
  • Not having normal use of physical faculties
  • Due to introduction of controlled substance
  • Drug, dangerous drug, or substance
  • Includes prescription medications
  • Includes over-the-counter medications
Covered Substances
Any Impairing Substance:
  • Marijuana/Cannabis products
  • Cocaine, methamphetamine, heroin
  • Prescription pain medications
  • Anti-anxiety medications
  • Sleep aids and muscle relaxers
  • Over-the-counter medications

Marijuana DWI in Texas

Important Note

Even as marijuana laws change across the country, driving under the influence of marijuana remains illegal in Texas with serious penalties.

Detection Challenges:
  • THC can be detected days/weeks after use
  • No reliable roadside impairment test
  • Blood tests show past use, not current impairment
  • Metabolites vs active THC distinction
  • Individual tolerance variations
  • Medical marijuana complications
Law Enforcement Indicators:
  • Bloodshot, glassy eyes
  • Dilated or constricted pupils
  • Odor of marijuana
  • Slow reaction times
  • Impaired coordination
  • Altered perception of time

Prescription Drug DWI

Legal Prescription ≠ Legal to Drive

Having a valid prescription does NOT provide legal protection if the medication impairs your driving ability.

High-Risk Medications:
  • Opioid pain relievers: OxyContin, Percocet, Vicodin
  • Benzodiazepines: Xanax, Valium, Ativan
  • Sleep aids: Ambien, Lunesta
  • Muscle relaxers: Flexeril, Soma
  • Anti-seizure: Some epilepsy medications
  • Antihistamines: Benadryl, cold medicines
Contributing Factors:
  • Combining multiple medications
  • Mixing medications with alcohol
  • New prescription adjustment period
  • Dosage changes or increases
  • Age-related sensitivity changes
  • Food and timing interactions
Defense Considerations:
  • Following doctor's instructions
  • No warning labels about driving
  • Unexpected adverse reactions
  • Medical necessity vs alternatives
  • Tolerance and routine use
  • Drug interaction effects

Drug Recognition Experts (DRE)

What is a DRE?

Drug Recognition Experts are specially trained officers who evaluate suspected drug impairment when alcohol is not detected or doesn't explain observed impairment.

12-Step DRE Evaluation:
  1. Alcohol influence review
  2. Interview with arresting officer
  3. Preliminary examination
  4. Eye examinations (HGN, VGN, LOC)
  5. Divided attention psychophysical tests
  6. Vital signs (blood pressure, pulse, temperature)
  7. Dark room examinations (pupil size)
  8. Muscle tone examination
  9. Check for injection sites
  10. Subject interview
  11. Analysis and opinions
  12. Toxicological examination

Drug Testing and Evidence

Blood Testing
Most Common for Drug DWI:
  • Can detect wide range of substances
  • Shows presence but not necessarily impairment
  • Different detection windows for different drugs
  • Requires specialized laboratory analysis
  • Chain of custody issues
  • Degradation over time
Urine Testing
Less Reliable for DWI:
  • Shows past use, not current impairment
  • Longer detection windows
  • Privacy concerns during collection
  • Easier to challenge reliability
  • May show metabolites only
  • Dilution and contamination issues

Drug DWI Defense Strategies

Challenge Testing
  • Blood draw procedures
  • Chain of custody issues
  • Laboratory contamination
  • Testing equipment reliability
  • Analyst qualifications
  • Sample degradation over time
Question Impairment
  • Presence vs impairment distinction
  • Therapeutic levels vs impairing levels
  • Tolerance from regular use
  • Medical condition explanations
  • Alternative causes of symptoms
  • DRE evaluation reliability
Medical Necessity
  • Doctor's orders and instructions
  • Lack of impairment warnings
  • Unexpected adverse reactions
  • Emergency medical situations
  • Drug interaction complications
  • Involuntary intoxication

Penalties for Drug DWI

Same as Alcohol DWI:
  • Class B misdemeanor (first offense)
  • Up to 180 days jail
  • Fine up to $2,000
  • Driver's license suspension
  • DWI education program
  • Ignition interlock device (if applicable)
  • Enhanced penalties for repeat offenses
  • Probation and community service
  • Drug assessment and treatment
  • Permanent criminal record
Additional Drug Charges:

If illegal drugs are found during the arrest, you may face separate possession charges in addition to the DWI.

Facing Drug-Related DWI Charges?

Drug DWI cases involve complex scientific evidence and specialized testing. You need an attorney experienced in challenging drug impairment cases.

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