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5 Questions About ‘Weed DUI’ Answered


5 Questions About ‘Weed DUI’ Answered

Many people assume chemical testing for THC is as simple and reliable as testing for blood alcohol content (BAC), but in reality it is much more complex.

Even in states that decriminalize medical or adult-use of cannabis, police can still arrest you for driving under the influence. That may not come as much of a surprise: most people know driving impaired is illegal, regardless of the substance. But many people don’t realize how difficult it is to chemically test for cannabis intoxication.

Here’s the answer to five big questions you might have about “weed DUI.”

1. What do state laws currently say about the limits for marijuana impairment?

Washington State, Colorado, California — and a number of other states with laws allowing for the medicinal or recreational use of cannabis — also have laws that address impaired driving. Much like drunk driving laws, these statutes give police two ways to determine whether a driver is impaired:

●     Observed Impairment: Trained officers use field tests and observe driver behaviors and judge the impairment of a driver.

●     Chemical Test Results: While there is no standard legal limit of active tetrahydrocannabinol (THC) as there is with alcohol, several states accept five nanograms of active THC as the limit. When a blood test shows levels above this limit, the driver often faces charges.

While these are generally accepted ways to identify a driver impaired by marijuana use, both of these methods have their problems.

2. How reliable is observed impairment as a method of determining marijuana use?

States with “stoned driving” laws typically train law enforcement officers to detect the effects of drugs on the body. In Colorado, a program known as Advanced Roadside Impaired Driving Enforcement (ARIDE) provides this training. Officers learn to spot and screen for dozens of potential indicators of impairment.

However, many people question the reliability of observational testing; it is more difficult to prove in court than a chemical test, and many times it comes down to the judgment of an officer who may or may not actually have the skills to determine the driver’s impairment.

3. What type of marijuana chemical testing do police rely on most frequently?

While arrests based on observed impairment are legal, most police departments also conduct chemical testing. This blood test checks for the THC level in whole blood, and if you exceed the legal limit in your state you may face impaired driving charges.

While this may seem similar to BAC testing, the difference is that results from BAC tests accurately show how much the driver recently drank. But residual THC can remain in your system for weeks or months after marijuana use, and there is usually some level of THC present in a regular user.

Still, a recent AAA Foundation study found that even blood tests looking only for active THC (and not including residual THC from previous use) may not be reliable. According to the study, these samples are often unreliable because it takes an average of 165 minutes from the time a stop occurs until the blood draw. This prolonged delay can lead to inaccurate results.

4. Are there better chemical testing options for marijuana impairment?

The obvious choice for more accurate testing results would be a device that serves as a sort of Breathalyzer for marijuana and other drugs. To this end, police departments across the country are beginning to utilize the Dräger DrugTest 5000 and other similar devices for roadside drug testing. This type of device is in use in Los Angeles and San Diego, and other police departments in California are testing a mouth-swab device.

These devices allow police to swab the inside of a driver’s cheek and test the swab onsite. The DrugTest 5000 checks for the presence of six types of drugs, including detecting whether there is active THC in the body. It takes only a few minutes to return results. A positive result would likely lead to a warrant for a blood test to identify the exact amount of drugs in the driver’ system.

5. How could these methods change in the future?

It took decades to reach our current national standards for drunk driving, so it’s no surprise that reaching a consensus on measuring and enforcing marijuana impairment could take several more years. The best thing you can do to protect yourself is never drive while impaired by drugs or alcohol.

Further, stay on top of local and state laws, and developments that relate to testing technology. Understanding how law enforcement determines marijuana impairment — and the problems with those methods — could play a major role in your case if you are ever falsely accused of driving under the influence.

TELL US, what’s your stance on “weed DUI?”



  1. Linda

    March 5, 2019 at 12:34 am

    I barely smoke, and I supposedly had 18 nanograms of THC in 1 milliliter of blood.
    Think about the person who smokes all day long, just to function properly in life, their nanograms have to be thru the roof.
    I am going thru a DUI-Marijuana Case right now. Its not fun. Its like being treated like a criminal, when I am not a criminal. Its a first offense situation, and no leniency allowed….because the government says so.
    Who set these laws? Do they smoke? Do they ingest any THC in their bodies? before they decide on limits. Each person who ingests marijuana in any form builds up a tolerance, and for this reason alone the 5 nanograms in absurdly too low, it should be 5000, not 5. Bring on the Hate!
    We are supposed to wait 2 hours after smoking to even consider driving.
    Does anyone ask that of a drinking Alcohol person? No they get a Last Call to order more alcohol, then they drive. How is that fair to your Marijuana Smoker…..we have to wait 2 hours.
    Again who created these laws? And why is driving accepted right after a person drinks.
    Marijuana consumers are being targeted by the law. If a person has to wait 2 hours, you think they are not going to continue smoking….Get Real.
    We need to change the laws in Washington State #ChangeLaw

  2. Chad

    June 2, 2017 at 5:10 pm

    Marijuana is too heavy of a substance to be functional while driving. However, they’re already implemented new technology to combat this with a company called Quanta. They standardized cannabis effects and removed the negative aspects of a traditional “high”. It’ll be interesting to see how the government takes to something like this, as they really don’t have any excuse anymore to keep it as a schedule 1 drug. Check em out

    • jim

      December 6, 2017 at 9:40 pm

      Chad quanta looks like total nonscience
      I would love to see their patents

    • David Stern ❤️

      January 23, 2018 at 6:03 pm

      Extremely informative. I have been smoking weed and one way or another since fourth grade. I drive the freeways of orange county and without weed I would’ve killed somebody for sure right now thank God marijuana works and all driving situations

  3. Matt McLaughlin

    May 31, 2017 at 5:36 pm

    You mentioned the need for a warrant in the case of whete a blood draw is desired . Good for you.

  4. Denise A. Valenti

    May 30, 2017 at 4:17 pm

    More research is needed and tessts of function that are simple and objtive need to developed. The data out of the state of Washington reports an increase in fatal crashes specific to marijuana. What is chilling is that they are also reporting a greater harm to innocent pedestrians, bicyclist and other drivers when compared to alcohol.Those testing positive for marijuana alone, not alcohol or other drugs, are FIVE TIMES more likely to kill someone other than themselves compared to a driver testing positive for alcohol.
    Tests of function are desperately needed so as to obtain convictions and remove these dangerous drivers from the road. IMMAD – Impairment Measurement Marijuana and driving is a simple app for a tablet that objectively measures functional impairment. It measures the visual field deficits (HUGE BLIND SPOTS or TUNNEL VISION) that occurs with marijuana use. Marijuana has been shown to significantly impair the eye retinal ganglion cells. IMMAD – Impairment Measurement Marijuana and Driving, measures this. IMMAD and other tests of function need further development and studied so as to have better tools for law enforcement to use in dealing with marijuana impaired driving.

    • ALLAN

      October 1, 2017 at 1:52 pm

      Are you a smoker though?

    • Danielson Mcjackers

      January 9, 2018 at 4:50 pm

      That’s bullshit, you see how crazy alcoholics are now look at the stoners. Think about what you’re saying. You’re for sure anti-marijuana like what did the plant ever do to you.

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