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Drug-Related DWI

The legal definition of intoxicated in Texas under Texas Penal Code § 49.01(2) means “not having the normal use of mental or physical faculties by reason of the introduction of alcohol” into the body. The definition also includes by reason of the introduction of “a controlled substance, a drug, a dangerous drug, a combination of two or more of those substances, or any other substance into the body.” When a person is under the influence—whether it is because of alcohol or a different drug—while operating a motor vehicle in a public place in Texas, he or she can be arrested for driving while intoxicated (DWI).

Many DWI arrests involve alcohol and evidence of the “per se” (Latin for “by itself”) definition of intoxicated as a person having a blood alcohol concentration (BAC) of 0.08 or more. DWI offenses involving alleged offenders who are under the influence of a controlled substance (commonly referred to as “drugged driving” crimes) are much more complicated because Texas has no such per se limits when it comes to controlled substances, so many arrests are based purely on the observations of arresting officers.

Lawyer for Drug-Related DWI Arrests in Conroe, TX

If you were arrested for drugged driving in Montgomery County or Harris County, it is in your best interest to quickly seek legal representation. Evans & Powell, PLLC aggressively defends clients charged with DWI offenses in Oak Ridge North, Cut and Shoot, The Woodlands, Spring, Shenandoah, Panorama Village, Porter Heights, Willis, and many surrounding areas of Harris County and Montgomery County.

Sean Evans and Frank Powell are experienced criminal defense attorneys in Conroe who can investigate all the circumstances surrounding your arrest and fight to possibly get the criminal charged reduced or dismissed. Call (713) 622 - 2000 today to have our lawyers review your case and discuss all of your legal options during a free initial consultation.

Overview of Drug-Related DWI Crimes in Montgomery County

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Types of Drug-Related DWI Charges in Texas

All DWI violations, alcohol and drug-related, are violations of Texas Penal Code § 49.04. Drug-related DWI offenses carry the same criminal penalties as alcohol-related DWI crimes.

Some of the most common types of drugged driving crimes include:

  • Marijuana DWI
  • Controlled Substance DWI
  • Prescription Drug DWI

The type of drug that is involved in an alleged DWI offense can be important because a prosecutor is still required to prove a person’s intoxication beyond a reasonable doubt. When a person is accused of drugged driving, positive blood or urine tests may still be refuted when it can be proven that the alleged offender was not under the influence of the controlled substance when he or she was driving.

According to the Mayo Clinic, the average detection times of some controlled substances are as follows:

Type of Drug

Detection Time


One day

Lysergic Acid Diethylamide (LSD)

One day

3,4-Methylenedioxymethamphetamine (MDMA, Ecstasy, or Molly)

Two days


Two days


Three days


Three days


Three days


Three days

Marijuana – Single Use

Three days


Three days


Three days


Three days


Five days

Marijuana – Moderate Use (multiple times per week)

Five days


Seven days

Phencyclidine (PCP)

Eight days


10 days

Marijuana – Heavy Use (daily)

10 days

Marijuana – Chronic Heavy Use

30 days

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Drug Recognition Experts in Montgomery County Drug-Related DWI Cases

Many drugged driving arrests involve the use of Drug Recognition Experts (DREs), police officers are trained to identify drug impaired drivers. DREs are commissioned Texas peace officers who have at least two years of service and have completed Standardized Field Sobriety Tests (SFST) training as well as a reasonable DWI background and completion of a program involving pre-school, DRE school, and field certification.

DREs perform a 12-step battery of tests on people suspected of being under the influence of a controlled substance. The typical 12-step process involves:

  • Breath Alcohol Test;
  • Interview of the Arresting Officer;
  • Preliminary Examination;
  • Examination of the Eyes;
  • Divided Attention Psychophysical Tests;
  • Examination of Vital Signs;
  • Dark Room Examinations;
  • Examination for Muscle Tone;
  • Examination for Injection Sites;
  • Subject’s Statements and Other Observations;
  • Opinions of the Evaluator; and
  • The Toxicological Examination.

Despite the variety of tests that DREs perform, it can be incredibly problematic for alleged offenders to have DREs conduct interviews of arresting officers before partaking in many of the tests. Conversations with police officers can lead to some confirmation bias in subsequent testing.

Additionally, many DREs are inherently unqualified to understand medical conditions—namely symptoms of complex medical conditions that may appear to be the result of supposed drug use.

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Texas Drug-Related DWI Resources

10 myths about drugged driving | Texas District & County Attorneys Association (TDCAA) — The TDCAA is a nonprofit organization that produces continuing legal education courses for prosecutors, their investigators and key personnel, provides technical assistance to the prosecution community and related criminal justice agencies, and serves as a liaison between prosecutors and other organizations. View a July-August 2012 article discussing some of the misconceptions about driving while impaired by drugs. The article discusses blood samples, quantitation relating to impairment, and identifying drugged drivers.

The International Drug Evaluation and Classification (DEC) Program — The National Highway Traffic Safety Administration (NHTSA) initiated DEC pilot programs in four states in 1987 after the program originated in Los Angeles in the 1970s. All 50 states, the District of Columbia, Canada, and the United Kingdom now participate after NHTSA and the International Association of Chiefs of Police expanded the program. Visit this website to learn more about DRE certification and find answers to frequently asked questions.

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Evans & Powell, PLLC | Conroe Drug-Related DWI Defense Attorney

Were you arrested for drugged driving in Harris County or Montgomery County? You will want to contact Evans & Powell, PLLC as soon as possible.

Conroe criminal defense lawyers Sean Evans and Frank Powell represent residents of and visitors to communities throughout Montgomery County and Harris County, such as Willis, Woodbranch, The Woodlands, Spring, Patton Village, Pinehurst, Splendora, Magnolia, and many others.

You can have our attorneys provide a complete evaluation of your case when you call (713) 622 - 2000 or fill out an online contact form to receive a free, confidential consultation.

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Evans & Powell, PLLC