What to Know About Drug-Impaired Driving

There has been a lot of media attention surrounding drunk driving and how people should not drive after having an alcoholic beverage. But what about consumption of marijuana and other drugs? How does that affect driving?

Drugged driving is illegal. Driving impaired by legal or illegal drugs is against the law in all 50 states and the District of Columbia. Recreational drug use is illegal in Texas, but even in states that have legalized marijuana, it is still illegal to drive under the influence of the drug.

Still, drivers do get behind the wheel while impaired by drugs. A survey by the National Highway Traffic Safety Administration in 2013 found that 20% of surveyed drivers tested positive for potentially impairing drugs. 

Drug Impairment

Marijuana can impair driving by affecting reaction time, attention, coordination, and judgment. The main ingredient, THC, alters how the brain processes information, making it harder for drivers to track moving objects, stay in their lane, and respond quickly to sudden hazards. Drivers may experience delayed braking, poor distance perception, and difficulty multitasking, such as steering while monitoring traffic signals.

Marijuana can also cause drowsiness or altered time perception, leading drivers to misjudge speed or gaps in traffic. While some users believe driving slower compensates for impairment, reduced reaction time still increases crash risk, especially in complex or emergency situations.

Other drugs can also cause dangerous effects. For example, cocaine and methamphetamine can make drivers more aggressive and reckless. Using multiple drugs at the same time, including alcohol, can amplify the effects of impairment.

It is also important to note that some prescription and over-the-counter medicines can cause extreme drowsiness, dizziness, and other side effects that can make driving unsafe. Read and follow all warning labels before driving.

How to Gauge Drug Impairment

Alcohol impairment is determined by a Breathalyzer device, but no such tool exists for gauging drug impairment. Because of this, gauging drug impairment involves evaluating a combination of observable behavior, physical indicators, and scientific testing, rather than relying on a single measure.

Law enforcement typically starts with driving behavior, such as lane drifting, delayed braking, or erratic speed changes. During a stop, officers assess physical and cognitive signs including bloodshot eyes, poor coordination, slowed reaction time, confusion, or difficulty following instructions.

Standardized field sobriety tests help identify impairment, though they are less precise for drugs than alcohol. In more complex cases, a Drug Recognition Expert may conduct a structured 12-step evaluation examining vital signs, eye movement, and muscle tone. Toxicology tests (blood or urine) can confirm drug presence, but do not always correlate perfectly with real-time impairment, making behavioral evidence critical.

Contact a Personal Injury Lawyer

Prescription and illegal drugs can cause impairment while behind the wheel, and drivers need to understand the risks involved.

Have you been in a crash caused by an impaired driver? If so, a Houston auto accident attorney from The West Law Office, PLLC can help you gather the evidence you need to prove your case. Call (281) 347-3247 or fill out the online form to schedule a consultation.

Source:

nhtsa.gov/risky-driving/drug-impaired-driving