Marijuana DUI Facts

Marijuana and Cars

It is illegal:

  • to drive under the influence of any drug, including marijuana. Vehicle  Code § 23152(f)
  • to smoke marijuana while driving a car, and
  • for a passenger to smoke marijuana while riding in a car. Health & Safety Code § 11362.3(a)(7) & (8)
  • to possess an open container of cannabis while driving. Health & Safety Code § 11362.3 a(4)
  • to possess, while driving a motor vehicle upon a highway … a receptacle containing cannabis … which has been opened or has a seal broken, or loose cannabis flower not in a container Vehicle Code § 23222 (b)(1).


It is not illegal for a person 21 years old and older to possess and transport cannabis in an amount not more than 28.5 grams. Health & Safety Code § 11362.1 (a)(1). The law permits possession and transportation of up to 28.5 grams of cannabis in a car. People v. Shumake 45 Cal. App. 5th Supp. 1.

Health and Safety Code section 11362.1 states that “no conduct deemed lawful by this section shall constitute the basis for detention, search, or arrest.”

It is estimated that 275 million people used illicit drugs, such as cannabis, in 2016, Cannabis is most used with 192 million users.

In July 2017, Richard P. Compton wrote “Marijuana-Impaired Driving – A Report to Congress” sponsored by the National Highway Traffic Safety Administration.

Compton notes, “the primary psychoactive substance in marijuana is delta-9-tetrahydrocannabinal (THC).” However, realize “THC is one of over 500 known compounds in the cannabis plant, including more than 80 other cannabinoids.”

Any compound found in the blood with the same molecular formula can cause a false positive. THC and non-active CBD have the same molecular formula.  This is called isobaric interference.

Compton cites a 2007 publication,Human Cannabinoid Pharmacokinetics, by Marilyn A. Huestis. In that piece, the author notes,

“Cannabis sativa contains over 421 different chemical compounds, including over 60 cannabinoids …”

This may be the reason why the plant is also called 420.

Furthermore, Compton’s report explains the difference between how the human body metabolizes alcohol compared to THC.  This is how we get the information about how THC stays in your blood for up to 30 days:

“While ethyl alcohol is readily soluble in water, and hence blood, THC is fat soluble. This means that once ingested, THC is stored in fatty tissues in the body and can be released back into the blood sometimes long after ingestion. Some studies have detected THC in the blood at 30 days post ingestion (Heustis, 2007). Thus, while THC can be detected in the blood long after ingestion, the acute psychoactive effects of marijuana ingestion last for mere hours, not days or weeks.”

Does THC make you too impaired to drive?

According to the report to Congress sponsored by the Federal Government NHTSA:

An interesting finding from this research is that after smoking marijuana, subjects in most of the simulator and instrumented vehicle studies on marijuana and driving typically drive slower, follow other cars at greater distances, and take fewer risks than when sober.

Unfortunately these facts probably won’t prevent you from getting arrested for driving under the influence of marijuana.

If that happens in Southern California, contact The Law Office of Richard Wagner.

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