Joseph P. Hougnon, Attorney at Law

Marijuana DUID’s and Per Se THC Limits Part 1


Reefer Madness – Science vs. Hysteria

Alcohol-Related Per Se Limits

If you’re arrested for an alcohol-related Driving Under the Influence charge (DUI) and your blood-alcohol content (BAC) is proven to be .08% or more, you are presumed guilty of a DUI pursuant to California Vehicle Code (CVC) section 23152(b). This is often referred to as the “legal limit.”

Every state in the U.S. has adopted 08% BAC “per se” limits for alcohol-related DUI’s.

Essentially, per se laws shift the burden of proof to the defense, if a driver’s BAC is at or above the per se limit. Unless the Defense presents evidence at trial to rebut the presumption of guilt, the District Attorney may be able to prove their case without any proof of impaired driving.

But, per se laws are a departure from the usual presumption of innocence we all take for granted in criminal law.

Every state also has a “catch-all” provision designed to cover those circumstances where the person is below 0.08%, but the person still appears impaired as defined by law.

CVC section 23152(a), makes it a crime in California to drive “under the influence” of alcohol”. Under the influence” means that your physical or mental abilities are impaired so that you can no longer drive as well as a normal cautious sober person.

Therefore, even if the driver’s BAC was below .08% at the time of driving, the District Attorney may still be able to prove their case if they can demonstrate there is enough evidence of impaired driving. Even so, a driver’s presumption of innocence remains intact if their BAC is below the legal limit and they are charged with violating CVC section 23152(a).

While opponents have some valid arguments against the one-size-fits-all .08% BAC per se standard in alcohol-related DUI’s, there are at least some scientific bases and studies to support the law.

Still, depending on the circumstances and a person’s particular body chemistry, it’s arguable per se BAC limits in alcohol-related DUI’s can lead to the arrest and conviction of some drivers who are not impaired at all.

Drug-related DUIs (DUID’s)

In contrast, most states, including California, do not have per se limits for Driving Under the Influence of Drugs (DUID) cases. If you have drugs in your system and you’re arrested for suspicion of DUID in California, the District Attorney will have the burden to prove beyond a reasonable doubt your ability to drive was impaired, as they do in alcohol-related DUI’s, where the driver’s BAC is below .08% or more [CVC section 23152(a)].

Until recently, CVC section 23152(a) also covered situations involving a person under the influence of drugs, or under the combined influence of alcohol and drugs.

However, the law changed on January 1, 2014 when two new sections of the CVC took effect. The new statutes specifically address those charged with driving under the influence of drugs, including prescription medications in cases where it can be shown that those medications impaired the driver, and driving under the influence of a combination of alcohol and drugs.

In California, CVC section 23152(e) makes it is unlawful for a person who is under the influence of any drug to drive a vehicle, while CVC section 23152(f) makes it unlawful for a person who is under the combined influence of any alcoholic beverage and drug to drive a vehicle. As with alcohol-related CVC section 23152(a) DUI’s, under the influence” means that your physical or mental abilities are impaired so that you can no longer drive as well as a normal cautious sober person.

Therefore, in California, if you’re charged with a violation of CVC section 23152(e) or (f), the District Attorney still has the burden of proof – they must prove that your ability to drive was impaired at the time of driving, as defined by law.

If California were to pass a per se law for marijuana-related DUI’s, however, the presumption of innocence would no longer apply to those whose THC levels are at or above the threshold set by the legislature, as those who are driving with a BAC at or above the legal limit of .08% are presumed guilty by law in alcohol-related cases. Indeed, some states have taken this approach to Marijuana-Related DUID’s, enacting “per se” laws for drivers with relatively low levels of THC.

Colorado & Washington have passed per se limits for marijuana-related DUID’s. Drivers with THC levels in their blood equal 5 nl/Ml or more are presumed guilty of DUID’s.

However, as science and studies have shown, the effects of alcohol and marijuana are very different.

Igor Grant, Professor and Chair of Department of Psychiatry and Director, Center for Medical Cannabis Research, University of California, San Diego, published an article on theconversation.com on November 16, 2016.

According to Professor Grant, “while the effects of alcohol vary based on a person’s size and weight, metabolism rate, related food intake and the type and amount of beverage consumed. Even so, alcohol consumption produces fairly straightforward results: The more you drink, the worse you drive. Factors like body size and drinking experience can shift the correlation slightly, but the relationship is still pretty linear, enough to be able to confidently develop a blood alcohol content scale for legally determining drunk driving. Not so with marijuana.”

Professor Grant also noted, “unlike alcohol, evidence of cannabis use can linger long after its effects have worn off, particularly if people are regular users or consume a lot in a single episode. Among chronic users, it may not clear out of their systems for weeks. Therefore, unlike blood alcohol concentration, the presence and amount of different cannabis compounds in the blood or urine do not necessarily tell you whether the driver is impaired due to marijuana. Regular marijuana users tend to become accustomed to the drug, particularly in terms of cognitive disruption or psychomotor skills. Because they are accustomed to the drugs’ effects, this means they may function better relative to naïve users.”

As studies have shown, the one-size-fits-all per se approach to marijuana-related DUID’s flies in the face of actual science and will lead to the arrest of some drivers who are not impaired at all, as well as those who may not have consumed marijuana for several days, or even weeks.

Further complicating the issue is the fact that regular users tend to develop a tolerance to the impairing effects of the marijuana, despite the fact that they may have levels of THC in their blood that is far above the relatively low per se limits enacted in some states.
Will California follow suit and pass “per se” laws for marijuana-related DUID’s? Will politicians and law enforcement consider actual science and the consequences before passing legislation and enforcing per se laws similar to those enacted in Colorado and Washington? Let’s hope so. Potential injustices may result if they don’t.

Stay tuned for “Marijuana DUID’s and Per Se THC Limits” – Part 2.

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About the Author

Since 1996, Joe Hougnon, Esq. has provided the best legal services for DUI, Criminal charges & personal injury cases in northern California.