Driving Under the Influence of Marijuana in Texas 

Driving under the influence of marijuana is a growing concern in Texas, and we at the Law Office of David D. White, PLLC, our Austin DWI Lawyers are here to help. Texas has strict laws and harsh penalties for impaired driving, regardless of marijuana’s legalization in other states. A charge for driving under the influence of marijuana can lead to serious consequences like fines, license suspension, or even jail time. We understand how overwhelming this can be, and we’re here to explain the laws, outline your options, and guide you through the process to help protect your future.

Driving While Intoxicated Marijuana Laws in Texas Versus Other States 

Texas treats driving under the influence of marijuana (or any drug) as a serious offense, treating it on par with alcohol-related DWIs. According to the Texas Penal Code Sec. 49.04, a driver is legally considered intoxicated if they lose the regular use of their mental or physical faculties due to the consumption of drugs, alcohol, or a combination of the two. This means that even if a driver feels capable of operating a vehicle, any noticeable impairment can lead to charges.  

Unlike some states where marijuana is legal and clear THC limits are established, similar to the blood alcohol concentration (BAC) limits for alcohol—Texas does not have a specific legal limit for THC while driving. This lack of a measurable threshold creates challenges for drivers and law enforcement. Officers cannot rely on objective measurements like a breathalyzer for THC. Still, they must instead observe impairment through field sobriety tests, behavior, or other forms of circumstantial evidence, such as the presence of marijuana in the vehicle or admission of use by the driver. 

In states where marijuana legalization has led to the establishment of specific THC limits, such as Colorado or California, there is a more transparent framework for determining impairment. For example, these states typically use a certain amount of THC per milliliter of blood as the legal threshold, similar to how BAC is measured for alcohol. However, in Texas, marijuana remains illegal, and the state adopts a zero-tolerance approach when it comes to driving under the influence. This means that any detectable use of marijuana or suspicion of impairment while operating a vehicle may result in prosecution and stiff legal penalties. Drivers are encouraged to avoid any drug use before driving to prevent these serious consequences.

Signs That a Driver is Driving Under the Influence of Marijuana 

Determining whether marijuana use has impaired a driver’s ability involves observing specific behaviors and physical signs that indicate potential impairment. Law enforcement officers (classified as Drug Recognition “Experts”) are trained to recognize these signs, which may include: 

• Driving erratically, such as weaving between lanes, driving too slowly, or exhibiting delayed reactions to traffic signals or road hazards. 
• The strong odor of marijuana inside the vehicle could indicate recent use. 
• Physical signs like bloodshot or watery eyes are commonly associated with marijuana use. 
• Slurred speech, slowed motor responses, or difficulty focusing can impair a driver’s ability to react appropriately to road conditions. 
• The presence of marijuana paraphernalia, such as rolling papers, pipes, or cannabis containers, may serve as evidence of use. 

Officers who suspect impairment can conduct field sobriety tests (FSTs) to assess a driver’s coordination, balance, and ability to follow instructions. These tests often include walking in a straight line or standing on one leg. However, identifying marijuana impairment is more challenging than alcohol intoxication. Marijuana’s effects vary widely, and there is no standard roadside test to measure THC, its psychoactive compound. Some signs of impairment may also be subtle, making detection during traffic stops harder. This highlights the need for better training and careful evaluations for law enforcement officers.

Measuring Intoxication and “No Refusal” Programs 

Unlike alcohol intoxication, which can often be quantified through a breathalyzer test, measuring marijuana impairment presents unique challenges. THC, the psychoactive component in marijuana, can remain detectable in blood or urine long after its impairing effects have worn off, making testing more complex. 

Texas law enforcement occasionally employs “No Refusal” programs, especially during holiday periods or weekends when impaired driving is more likely. According to NHTSA’s information about “No Refusal” initiatives, these programs allow officers to obtain expedited warrants for blood tests if a driver refuses to comply with initial testing. Blood testing can detect traces of THC and help strengthen the case against impaired drivers. 

Under these programs, drivers may feel their rights are being violated. However, in Texas, refusing a blood or breath test often results in automatic license suspension, and the evidence gathered through these means is admissible in court. 

DWI and DUI of Marijuana Evidence and Per Se Definitions of Intoxication 

Driving while intoxicated (DWI) and driving under the influence (DUI) may seem synonymous but can have subtle distinctions in Texas. For individuals under 21, DUI charges often result when any trace of drug or alcohol use is detected while driving. DWIs typically involve more significant levels of intoxication or impairment, irrespective of age. 

Evidence plays a central role in building a case for driving under the influence of marijuana. Law enforcement may rely on these types of evidence in Texas DWI cases:

• Field Sobriety Test results, which aim to showcase physical or mental impairment. 
• Blood or urine tests are used to detect THC levels in the system. 
• Police observations include statements from the arresting officer regarding the driver’s appearance or behavior. 
• Dashcam or bodycam footage. 
• Witness testimonies supporting the suspicion of impaired driving. 

Texas does not provide a per se standard of intoxication for THC, unlike alcohol (with a limit of 0.08% BAC). Without a clear numerical standard, prosecutors must build their case using evidence of impairment rather than relying solely on test results. 

While defenses exist, such as questioning the accuracy of drug tests or the legality of the traffic stop, navigating these charges requires experience and strategic legal guidance. 

“When you hire this firm, you get a named attorney from intake through resolution. The lawyer who explains your case at signing is the lawyer who appears at every setting. We do not hand cases off to whoever is at docket call.”

David D. White

Austin Criminal Defense Lawyer

Tell Us About Your Case 

Facing charges related to driving under the influence of marijuana in Texas can be overwhelming, but you don’t have to face it alone. Our Texas DWI attorneys at the Law Office of David D. White, PLLC, are committed to helping you understand your legal rights and building the strongest possible defense for your case. Contact us today at (512)-369-3737 to discuss your situation. We’re here to provide personalized support every step of the way. 

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