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How Is Marijuana Detected in a DWI?

Doug Norwood Blog

In Arkansas, a person can be charged with a DWI if they were intoxicated by marijuana when operating or in physical control of a motor vehicle. In DWI-alcohol cases, police officers often rely on the results of a breath test to determine blood alcohol concentration (BAC). If results show that BAC was at or above 0.08, the motorist is presumed to have been intoxicated.

Presently, no reliable breath testing device exists to accurately measure marijuana levels. Even if such machines were on the market, it wouldn’t matter in Arkansas. The state’s DWI laws do not have a THC threshold for presuming someone was intoxicated while driving.

So, what methods do law enforcement officials use to detect marijuana, and how does the prosecutor prove intoxication? Authorities may rely on measurements similar to those used in DWI-alcohol cases, such as blood, saliva, urine analyses, or officer observations. They may also use methods unique to DWI-marijuana cases, like a drug recognition expert testimony.

If you were charged with a DWI in Northwest Arkansas, call Norwood & Norwood, P.A. at (479) 235-4600 or contact us online to discuss your legal options.

How Can Someone Be Charged with a DWI of Marijuana in Arkansas?

A marijuana DWI is charged under the same statute as an alcohol DWI – A.C.A. § 5-65-103. The law provides that a person commits an offense when they operate a vehicle while intoxicated. Intoxication means that a person’s reaction, judgment, and motor skills are substantially altered because of the consumption of alcohol and/or a controlled substance like marijuana.

How Can Police Officers Tell That Someone Was Intoxicated by Marijuana?

As with an alcohol DWI, a marijuana DWI begins with a traffic stop. The police officer might notice something off about the person’s driving behaviors, giving them probable cause to pull the motorist over.

Signs that a person is intoxicated may include, but are not limited to:

  • Driving too slowly
  • Weaving between lanes
  • Braking too quickly
  • Failing to obey traffic laws

These driving behaviors are not unique to drivers intoxicated by marijuana. At this point, the officer would not know whether the motorist had consumed alcohol or weed before getting behind the wheel. However, as they approach the vehicle and interview the driver, the source of intoxication may be more apparent.

The officer might notice that the driver:

  • Has bloodshot eyes,
  • Is sleepy or lethargic,
  • Lacks coordination,
  • Is confused or unfocused, or
  • Is having trouble remembering things.

Roadside Breath Test Results

The indicators listed above aren’t unique to marijuana intoxication. A person under the influence of alcohol may also display these behaviors. The officer might administer a roadside breath test to determine whether the driver is high on weed or intoxicated by alcohol.

Breath tests measure the amount of alcohol in a person’s system. The device analyzes the person’s breath sample and generates an estimate of their BAC. As noted before, these machines are not yet designed to provide THC levels. The officer wouldn’t use it to detect marijuana. However, they might suspect that the driver smoked weed if they exhibited behaviors indicating intoxication but did not have a high BAC.

Observations by a Drug Recognition Expert

If the results of a breath test do not show that the driver had alcohol in their system, the officer might call on a drug recognition expert (if available in the area) to observe the driver. Drug recognition experts (DRE) are specially trained to determine whether someone is impaired by a controlled substance.

DREs may assess the driver’s behavior, conduct eye examinations, take their blood pressure, and analyze responses to various questions.

Blood, Saliva, or Urine Tests

Upon making an arrest for suspicion of marijuana DWI, law enforcement officials may direct drivers to submit to a blood, saliva, or urine test. These assessments can more accurately detect whether a person had weed in their system at the time of driving.

Marijuana can stay in a person’s system for weeks after it was consumed. Thus, the chemical test might indicate the presence of the substance, but the driver might not have been impaired by it. Prosecutors work hard to prove that the individual was intoxicated while operating a vehicle.

They may present evidence such as:

  • The arresting officer’s observations,
  • The chemical test results, and
  • Testimony from a DRE or other experts.

Call Our Firm Today

Marijuana DWI matters can be complex. Because of this, it’s important to hire a criminal defense attorney who can provide the legal guidance you need at every stage.

At Norwood & Norwood, P.A., we pursue available legal avenues to seek favorable results for our clients in Northwest Arkansas. Schedule a consultation by contacting us at (479) 235-4600.