The Dräger 5000 Cannot Prove Marijuana DUI

dui checkpoint duii marijuana cannabis
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One of the biggest concerns about marijuana reform is what effect, if any, it will have on public roadways. Marijuana opponents try very hard to convince the American public and elected officials that immediately following marijuana reform there will be an inevitable stoned driver epidemic the likes of which is something out of a horror movie. Those types of doomsday predictions were common leading up to legalization in Washington and Colorado, and continue to today, despite considerable evidence that fears about such an epidemic are unfounded.

The marijuana holy grail for law enforcement is a marijuana breathalyzer. Members of law enforcement are used to, and very familiar with, using a breathalyzer to measure the blood alcohol content of a suspect via their breath. Measuring impairment is very easy when it comes to alcohol. I once heard a researcher say that ‘alcohol is the perfect substance for the task of determining impairment from someone’s breath.’ That same researcher said that marijuana may be the hardest.

Proving the presence of marijuana is easy. A breathalyzer can indicate the presence of marijuana, a mouth swab can indicate the presence of marijuana, and a general awareness of one’s surroundings while applying logical reasoning can easily help someone know that marijuana has been consumed by a person. However, just because someone has marijuana on their breath does not mean that they are impaired. In many cases far from it.

I read a story today about the ‘Dräger 5000’ which is apparently in use in various jurisdictions across America, including ‘places such as Los Angeles, New York, Arizona and Nevada, as well as in other countries such as Australia, Belgium and Germany.’ The article was specifically discussing the roll out of the Dräger 5000 in San Diego over St. Patrick’s Day weekend. The Dräger 5000 involves gathering a mouth swab sample from the suspect, and putting it through the machine which is the size of ‘a mini bookshelf stereo system.’ The machine analyzes the sample, and indicates the presence of a controlled substance, but not the level of impairment, which makes the device basically like every other device that’s already out there.

The device is built to detect the presence of various substances, but the member of law enforcement quoted in the article made it clear what the real intent of using the device was for – marijuana. Per the Los Angeles Times:

“It’s a huge concern of ours with the legalization of marijuana that we’re going to see an increase in impaired drugged driving,” Police Chief Shelley Zimmerman said at a news conference Thursday near the Ingraham Street Bridge in Mission Bay, a common DUI checkpoint spot.

“We want to get these impaired drivers off the streets,” the chief said.

The Los Angeles Times article states that in order to determine impairment, law enforcement would need to draw the blood from the suspect’s arm, even though the suspect is innocent until proven guilty and could very well end up perfectly clean when the test results come back. I don’t know about you, but I don’t exactly like getting stabbed in the arm with a sharp instrument and having my blood removed when I’ve done nothing wrong.

Even if someone returns a positive result for the presence of THC in their blood, it still doesn’t prove impairment. That’s because of how THC is metabolized in the body. Depending on a multitude of factors, a person’s body can metabolize marijuana from active THC (which can indicated impairment) to metabolized THC in as quick as 2 hours. Metabolized THC can stay in the system for as long as 100 days in some cases, but active THC can only be detected in a person’s system for a very limited window of time.

A DUI investigation can take hours. If a driver hypothetically consumed cannabis then got behind the wheel and drove, and then was pulled over by an officer, tens of minutes would be spent with the officer interacting with the subject, explaining the belief of marijuana impairment, and gathering paperwork (license, registration, etc.). Anyone who has seen this play out on the side of the road knows that there is always more than one officer involved, so a call for backup has to occur and depending on how long it takes for the second officer (usually a certified DUI recognition expert), a considerable amount of time could pass.

Once the second officer arrives, a series of field sobriety tests are performed. One of my professors in college was a DUI defense attorney, and he explained that law enforcement is trained to perform as many field sobriety tests on a subject as possible when it involves a suspected marijuana DUI, if for any reason to rule out other substances in an effort to build the case for marijuana impairment. After the field sobriety tests there is usually a huddle of the officers involved, they arrive at a conclusion, and in many cases, the suspect is placed into custody. In theory the Dräger 5000 could speed up that process by indicating the presence of marijuana earlier in the process, but that’s the only benefit of the device, the technology of which has been out there for quite some time.

From there the officers either take the suspect to their police station for a certified person to draw a blood sample (a phlebotomist), or they call a mobile phlebotomist who comes to the roadside to perform the test. In either event, it takes more travel time by the person performing the blood draw. Then and only then, after considerable time has passed, will a valid determination of the presence of active THC be measured. In most cases a person’s body will have already metabolized the THC, at which point there’s no way to know if the person consumed before they got behind the wheel, or several weeks ago in the comfort of their own home and in no way operating a motor vehicle until impairment has long since passed.

Even if active THC is found in a person’s system, it does not indicate that the person is impaired, because heavy users consume so much more than infrequent users, and are not impaired. Setting a per se limit for active THC in a person’s blood is not a policy based upon sound scientific reasoning, because a heavy user may have a significant amount of THC in their system yet not have their motor functions impaired, whereas a newbie user would not even have enough THC in their system to register a positive drug test, yet be completely unfit to operate a motor vehicle. A per se limit for marijuana literally punishes the people that are the least likely to pose a danger on the roads, while at the same time failing to catch the people that are really a danger to themselves and other drivers short of one of them causing an unfortunate accident.

I am assuming that as marijuana reform spreads, draconian DUI checkpoints where people are mouth swabbed and bled against their permission will become more common. It’s part of the second phase of the fight to legalize marijuana. The effort doesn’t stop when a successful vote happens at the ballot box. Responsible marijuana consumers do not support people consuming marijuana to the point of impairment and then operating a motor vehicle. However, we also do not support laws and overzealous law enforcement crackdowns that unnecessarily punish people who have done nothing wrong.

Johnny Green
About Johnny Green 491 Articles
Johnny Green is a cannabis activist from Oregon. Johnny has a bachelor's degree in public policy, and believes that the message should always be more important than the messenger. #LegalizeIt #FreeThePlant


  1. You can see that the prohibitionists will promote per se limits and breathalyzers as the way to deal with “marijuana impairment.” This is bad law, not supported by science–it is only measuring exposure to the drug, not impairment. It is important to demand that legislators pass laws that mandate measurement of actual impairment. In order to fight against bad laws being passed, I have been working intensely this past year to demonstrate that impairment testing is feasible.

    I have developed a new public health app that measures impairment–it is called DRUID (an acronym for “DRiving Under the Influence of Drugs”) available now in the Apple App Store (Android version coming soon). DRUID measures reaction time, decision making, hand-eye coordination, time estimation and balance, and then statistically integrates hundreds of data points into an overall impairment score. DRUID takes just 5 minutes (and the 2-minute version should be available in a week or two). Our website is

    DRUID allows marijuana users (or others who drink alcohol, use prescription drugs, etc.) to self-assess their own level of impairment and (hopefully) decide against driving if they are impaired. Prior to DRUID, there was no way for an individual to accurately assess their own level of impairment. DRUID also demonstrates that it is feasible to measure impairment reliably by the roadside, not just exposure to a drug.

    DRUID was recently featured on NPR’s All Things Considered:

    Also on television:

    After obtaining my Ph.D. at Harvard, I have been a professor of psychology at UMass/Boston for the past 40 years, specializing in research methods, measurement and statistics.

    Michael Milburn, Professor
    Department of Psychology

    • Thanks for your work, I’m looking forward to trying the android version of your app once it comes out. I agree that cannabis DUIs should be based on impairment and not simply exposure. We need to do a better job of educating the public regarding cannabis and driving. The fact that the police are complaining on how hard it is to detect stoned driving without using some external device should help our argument that stoned driving is not the problem the prohibitionists make it out to be, on the other hand we need to accept that you are not a better driver stoned, you may be safe to drive but let’s not pretend it does not affect our driving.

      • I fully agree with you. I am against stoned driving. My DRUIDapp is to give people a tool, giving them information about themselves, so they can make a more deliberate decision to avoid driving when they are impaired.

    • ‘DRUID measures reaction time, decision making, hand-eye coordination, time estimation and balance, and then statistically integrates hundreds of data points into an overall impairment score. DRUID takes just 5 minutes (and the 2-minute version should be available in a week or two).’ I’m extremely wary of something like this too to be blunt. There are any number of factors, including stress or illness, that can influences such measurements. I get that psychology wants to pretend that it’s a science but it is so in name only. This is as much educated guess work as the cops huddled by the side of the road who think that someone’s drunk when they may in fact have a speech impediment.

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