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The problem: A driver who is impaired, can cause car accidents and people getting hurt. If a driver actually is impaired, and if that impairment was caused by marijuana, then that may be a DUI marijuana offense. And a conviction can result, with all the DUI consequences, including driver’s license revocation. While prevention is easy, after the arrest a DUI marijuana lawyer like Thomas Gallagher can help solve the problem.
Impaired Driving vs. DUI marijuana
When is a driver impaired? Impairment means that our performance is less than normal to the point of being unsafe. It could be less than normal for each one of us as an individual. Or, we could mean less than normal for the law’s mythical “reasonable person.”
If we’re talking about impaired “driving,” then the impairment must connect with driving, somehow. So, before we get to DUI marijuana, we begin with the threshold question: “Is the person’s driving impaired?”
Driving conduct
How can we tell if someone’s “driving” is impaired? Well, is the person driving poorly? Is it a “bad driving” case? If a driver gets into a car accident, most wonder, was that driver at fault? If not, a car accident does not show bad driving. But it may raise the question.
Or, a police officer may observe a driver driving badly. Swerving across three lanes of traffic might mean bad driving. Or, in isolation, the driver might have swerved to avoid hitting a deer. Good driving.
Police officers attempt to observe and document more than one instance of bad driving, to reasonably suspect impairment. This is the case in a DUI marijuana case as well.
Driver appearance
No bad driving: In some DUI cases, the police officer does not observe any driving, at all. For example, a person found near a car with a flat tire may arouse police suspicion. But the police did not observe any driving, good or bad.
Whether or not the police officer observes driving, they may still try to get evidence to probe for driver impairment. If they find evidence of recent marijuana use, police may investigate for DUI marijuana.
“Field Sobriety Tests:” field exercises
Police officers at a DUI stop ask the driver to perform “Field Sobriety Tests” (FSTs). (And the driver can decline to do them. No excuses necessary.)
Alcohol only: The National Highway Traffic and Safety Administration (NHTSA) standardized them as a screening test, but only for alcohol-impairment. NHTSA’s three Standardized FSTs are the “nine-step-walk-and-turn,” the “one-leg-stand” and the “Horizontal Gaze Nystagmus” (HGN) test. And none of them has been validated for marijuana.
Police sometimes “request” additional FSTs looking for evidence of DUI marijuana. They may attempt to get the driver to cooperate with these at the police station. And they may call in another officer to do their “Drug Recognition Evaluation” (DRE). But no driver can be required to submit to these unfair “tests.” The driver can refuse them without fear of penalty. So say “no, thanks.”
Police distract & observe driver
In addition, police will selectively document those observations of the driver that support a theory of intoxication. But they ignore observations supporting a theory of sobriety. Just about every DUI police report notes: bloodshot, “watery eyes,” and “odor of (alcohol) (marijuana)” Other common boilerplate notations include:
- fumbled for license, insurance card
- appeared nervous or tired
- used door for balance exiting
- used side of vehicle for balance
Preliminary Breath Test (PBT)
Most DUIs involve the odor of alcohol. The odor of alcohol alone is not enough for probable cause of DUI, without other observations consistent with impairment. If so, police officers often ask the driver to blow into a “Preliminary Breath Test.” The PBT is a small, portable breath-alcohol machine. Refusing the PBT can give the police probable cause to arrest. Blowing a 0.08 or more reading is also arrest probable cause.
In a traffic stop leading to a DUI marijuana investigation, police might also request the driver blow into a PBT. They will if the driver has an odor of alcohol.
Marijuana DUI police procedures
For DUI marijuana investigations, the usual DUI investigation is a bit different. Almost always, it begins with the police claim of an odor of marijuana. Then, the police ask questions about marijuana. Then, they search the driver and the car if they can.
See: How to Avoid a Marijuana Arrest in a Car
If police find marijuana, they may charge marijuana in a motor vehicle.
Or, if they find wax, concentrates, or THC edibles, they may charge a felony or gross misdemeanor possession, depending upon quantity.
After that, the FSTs, DRE exercises (or field exercises) become more important. Most DRE exercises relate specifically to drugs other marijuana.
Know your rights: Never do FSTs
Police cannot force anyone to do FSTs or DRE exercises. You can simply decline to do them. And you should not offer any excuses, either. Just tell the police officer that you won’t do any field exercises or Field Sobriety Tests (FSTs), at all. You don’t need a reason or justification. You don’t have to do them. They can only hurt you.
NHTSA does not claim any FSTs or DRE exercises are scientifically valid for marijuana. And the police officer is not a scientist or a medical doctor. It’s not a fair “test.” Police will note every imperfection to support the one conclusion. “Fail.” And they’ll ignore evidence, and the science, to the contrary. Don’t take that bait.
If you already did. Your DUI marijuana attorney can take steps to neutralize them. See my article: Avoiding a DWI: Stop Countermeasures.
Post-arrest: DRE
After an arrest at the roadside, the police officer takes the driver to either a hospital or a police station. There, sometimes a trained “Drug Recognition Evaluation” police officer will ask the driver to agree to undergo examinations consistent with the DRE protocol. But, in order to support a DUI marijuana charge, they think they need a urine or blood test. In reality, they need a blood test (or a refusal).
Urine or blood
To get a urine or blood test, police need a search warrant signed by a judge. Ask to call an attorney prior to giving any sample for testing. The marijuana DUI attorney on the phone can advise you about whether to submit a sample for testing; and about your right to an additional, independent test after theirs.
If you refuse a blood draw, police must offer the choice of a urine sample before labeling you a refusal. And, they must offer a blood test if you refuse urine, before charging you with a chemical test refusal crime in Minnesota.
Chemical test: DUI marijuana cases
Police must send the blood or urine sample to a lab for analysis. That will take time. Without the lab results, there is no evidence of marijuana or THC in the body. So, charges should wait for the lab results, if any.
Lab reports for THC & metabolites: In a suspected DUI marijuana case, the lab can test for many prescription and other drugs, including THC. In addition to THC, the lab report will show results for THC-metabolites.
What are metabolites?
When the body’s metabolism breaks down a chemical or drug into another chemical, it’s a metabolite.
Alcohol metabolites: For example, enzymes in the human body metabolize alcohol first into acetaldehyde, a toxic substance. Then, in a second step, our bodies metabolize acetaldehyde down to another, byproduct called acetate. Our bodies then break down Acetate into water and carbon dioxide for elimination.
Key take away: Metabolites of alcohol are not-alcohol.
Marijuana metabolites: The marijuana plant component that is psychoactive is THC. So, the lab tests the blood for THC (Δ9-tetrahydrocannabinol).
In addition, the lab tests for two metabolites of THC, “hydroxy-THC” (11-OH-THC) and “carboxy-THC” (THC-COOH). (In recent years the Minnesota BCA has added related cannabinoids and metabolites, such as Delta-8 THC to their lab panel. But these are of too little importance to discuss further here.)
Key take away: Metabolites of THC are not-THC. Rather, a THC metabolite is another, different chemical. The body makes it as a byproduct of breaking down THC into other chemicals. And while Hydroxy-THC can have psychoactive effect, the long-lived Carboxy-THC has zero psychoactive effect at all. But none of these, these, THC or THC-metabolites, prove impairment.
Ignorance about metabolites
Ignorance about the science of THC, metabolites and their effects leads to false charges of DUI marijuana. But Attorney Thomas Gallagher has helped clients get these cases dismissed.
The common confusion about this may stem from the use of “THC” in names of THC metabolites, “hydroxy-THC,” and “carboxy-THC.” So, remember:
- THC is the psychoactive ingredient in marijuana, can be psychoactive
- Metabolites of THC are not THC
- The short-lived metabolite Hydoxy-THC can be psychoactive
- The long-lived metabolite Carboxy-THC is not psychoactive at all
A lab test report includes levels for:
- THC
- Hydroxy THC, and
- Carboxy THC
- Other
So, then why test for metabolites? Because you can? It’s difficult to discern any relevance of Carboxy THC for purposes of DUI enforcement, other than potential to confuse some. After all, Carboxy THC:
- has zero psychoactive effect
- blood level rises after THC blood level declines
- remains detectable for over 30 days; not evidence of recent use
- can prove past use, but not recent use or impairment
Hydroxy-THC is detectable in blood up to 24 hours after last use, depending on method of ingestion. As a result, we can use Hydroxy-THC in combination with blood THC level to approximate a rough time range of last use. But this has little probative value to the issue of possible impairment.
No Retrograde Extrapolation
Alcohol: In DUI Alcohol cases, the theory of “retrograde extrapolation” (or, “back-extrapolation”), attempts to work backwards from the time of a known test level to estimate a driver’s blood alcohol level at the time of arrest, or time of an accident hours earlier. Then with multiple other known facts, such as the test subject’s gender, weight, etc., it attempts to “extrapolate” what the alcohol concentration level would have been in the past. This is possible, because blood alcohol is eliminated by the body at a fairly linear rate; and due to the high correlation between blood alcohol level and impairment.
Marijuana: But retrograde extrapolation is not scientifically valid for THC and marijuana. Why? D-9 THC is eliminated by the body at an exponential, non-linear rate; and has no correlation between blood THC level and impairment. The human body’s elimination of THC is rapid and non-linear. So “back-extrapolation is not an option due to the complex pharmacokinetic profile of THC.“ (Willie et al, 2010. Conventional and alternative matrices for driving under the influence of cannabis, Bioanalysis).
Urine tests in DUI Marijuana cases are useless
Urine tests show metabolites only. Why? They only show inert substances, not the psychoactive ingredient. If urine test lab reports did list Delta-9 THC, the level, if any, would be meaningless, possibly false, trace levels (extremely low) in urine. Remember, the issue in a DUI cases is “was the driver’s driving impaired by a specific drug such as alcohol or THC.” Since a Urine Test report will not indicate THC levels, the psychoactive ingredient in marijuana; it cannot be evidence of impairment caused by THC.
Minnesota Law Requires Urine if Blood Refused
Minnesota law currently requires police officers requesting a blood test in a DUI case, to offer a Urine Test if the arrested person refuses a blood test. Do you see the practical implication of the limitations of urine testing? A urine test won’t show Delta-9 THC. A future legislature could amend this. But ideally they would simply eliminate DUI urine testing in Minnesota, as almost all other states have already done.
If the driver refuses both blood and urine following a lawful request by a police officer, the driver may face criminal charges for DUI – refusal to provide a sample for chemical testing.
D-9-THC in blood does not show impairment, at any level
“One of the program’s objectives was to determine whether it is possible to predict driving impairment by plasma concentrations of THC and/or its metabolite, THC-COOH, in single samples. The answer is very clear: it is not.
US National Highway Traffic Safety Administration, Marijuana & Actual Driving Performance, 1993
Plasma of drivers showing substantial impairment in these studies contained both high and low THC concentrations; and, drivers with high plasma concentrations showed substantial, but also no impairment, and even some improvement.”
NHTSA and the scientific studies say, there is no correlation between blood plasma THC levels and impaired driving.
That seems counterintuitive to most people. Most people have personal experience with alcohol. Blood alcohol levels do roughly correlate with impairment. But alcohol and THC are quite different, in this way.
“THC’s effects differ qualitatively from many other drugs, especially alcohol. For example, subjects drive faster after drinking alcohol and slower after smoking marijuana. … Very importantly, our city driving studied showed that drivers who drank alcohol over-estimated their performance quality whereas those who smoked marijuana under-estimated it. …
US National Highway Traffic Safety Administration, Marijuana & Actual Driving Performance, 1993
“[S]ubjects in the marijuana group were not only aware of their intoxicated condition, but were … attempting to compensate for it. These … findings … support … the common belief that drivers become overconfident after drinking alcohol and … that they become more cautious and self-critical after consuming low doses of THC, as smoked marijuana.”
“… comparable to risks such as talking on a hands-free cellphone …”
Minnesota Statutes & DUI marijuana
Minnesota Statutes §169A.20 is the general DUI statute. Here are the most relevant parts:
“Subdivision 1. Driving while impaired crime; motor vehicle.
It is a crime for any person to drive, operate, or be in physical control of any motor vehicle, as defined in section 169A.03, subdivision 15, except for motorboats in operation and off-road recreational vehicles, within this state or on any boundary water of this state when:
(1) the person is under the influence of alcohol;
or
(8) the person is under the influence of cannabis flower, a cannabis product, a lower-potency hemp edible, a hemp-derived consumer product, an artificially derived cannabinoid, or tetrahydrocannabinols.Subd. 2. Refusal to submit to chemical test crime.
Minn. Stat. §169A.20 (2023)
It is a crime for any person to refuse to submit to a chemical test:
(1) of the person’s breath under section 169A.51 (chemical tests for intoxication), or 169A.52 (test refusal or failure; revocation of license); or
(2) of the person’s blood or urine as required by a search warrant under sections 171.177 and 626.04 to 626.18.
Penalties & consequences: DUI marijuana
The penalties and consequences of a marijuana DUI are similar to any Minnesota DUI case. For example, a fourth within 10 years is Felony DWI with a presumptive prison sentence.
There is one important difference, however. With an alcohol DUI, the state revokes your driver’s license immediately after a chemical test over the per se 0.08 limit. And it revokes your license upon a refusal to test. There is no per se limit for THC, however, and for good reason.
The science, and NHTSA agree, there is no specific THC level that correlates with impairment. In fact, some drivers drive better with THC than other drivers with no THC. As a result, a “per se” limit for THC would make zero sense. So, the state will not revoke your driver’s license before conviction for DUI marijuana, unless you refuse chemical testing. Attorney Thomas Gallagher can help you with questions about this.
Defenses: DUI marijuana cases
The hundreds of defenses available in any DWI case are also available in a marijuana DUI. But there are some defenses specific to DUI marijuana cases. These include evidence about THC and its metabolites, and the effect of THC on driving.
Question? Call Attorney Thomas Gallagher, 612 333-1500
Should you have a DUI Marijuana Attorney with specific training and experience? Attorney Thomas Gallagher has that. In fact, Thomas Gallagher teaches DUI Marijuana law in Continuing Legal Education (CLE) courses to prosecutors, defense attorneys and judges.
Minneapolis Criminal Defense Lawyer Thomas Gallagher is an expert DUI Marijuana defense attorney. He has won dismissals by judges considering his pretrial motions. And he has won not-guilty jury verdicts.
Link to view television interview of Attorney Thomas Gallagher on TPT Almanac discussing Marijuana DUI, 07/28/23.
More
The Myth of Marijuana DUI vs. Science
Marijuana Laws in Minnesota
Marijuana in a Motor Vehicle
How to Avoid a Marijuana Arrest in a Car: Nine Tips
Careless Driving | Reckless Driving – Charges & Defense