How does law enforcement know if you’re too high to drive? What California law says

Angela Rodriguez
·6 min read
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Though California has legalized the use of recreational marijuana, there are laws surrounding how much you can have and where you can use it.

When it comes to using then driving, how high is too high to drive? How does law enforcement test for a cannabis-induced DUI?

Here’s what California law states on driving under the influence of the recreational drug:

Marijuana effects while driving

According to the California Office of Traffic Safety website, marijuana can have the following effects on a driver:

  • Slows reaction time and ability to make decisions

  • Controls the part of the brain responsible for body movement, balance and coordination

  • Impairs judgment and memory

  • Negatively impacts attentiveness

  • Impacts perception of time and speed

“The effect of marijuana is strongest during the first 30 minutes after consumption,” the website states.

While these effects can be delayed if the marijuana is ingested rather than smoked, the website states people who drive immediately after using marijuana can increase their risk of getting into an accident by 25% to 35%.

Is there a legal limit for cannabis and driving?

California Vehicle Code 23152 states it is illegal for a person who is under the influence of drugs or alcohol to drive. That includes cannabis.

While California’s level of impairment for drunken driving is a blood alcohol concentration of 0.08% or higher for those of legal drinking age, there is no similar way law enforcement measures what is “too high.”

Matt Radke, a spokesperson for California Highway Patrol, said a person’s level of cannabis influence is subjective.

“When it comes to driving under the influence of cannabis much like with an alcoholic beverage, it is a totality of circumstances while driving,” Radke wrote in an email to The Bee.

A person would get pulled over to be tested for sobriety depending on their driving patterns.

If a person does have drugs in their system at the time they were driving, Radke said it would be determined by a blood test.

“Testing is ongoing to assist law enforcement with determining which level of cannabis in the system is too much to be driving,” Radke wrote.

Cannabis can be detected in a person’s blood system for up to 12 hours, according to the American Addiction Centers website.

Why doesn’t California have a set limit for driving under the influence of marijuana?

California law requires the driver to be under the influence of or affected by THC in order to be cited, according to the National Conference of State Legislature website.

However, testing for drug impairment can be irregular due to the limitations of drug-detecting technology and the lack of a set limit.

“Drugs do not affect people consistently,” the website states. “Drugs such as marijuana can also stay in the system for weeks, thus appearing in roadside tests while no longer causing impairment.”

In 2021, Dale Gieringer, the coordinator of California National Organization for the Reform of Marijuana Laws, said CHP convened an Impaired Driving Task Force to address these questions.

NORML is a Washington D.C.-based nonprofit organization established in 1970 and serves as an advocate for marijuana consumers to provide “a voice in the public policy debate for those Americans who oppose marijuana prohibition and favor an end to the practice of arresting marijuana consumers.”

CHP, the reform organization and other interested groups participated in a drug-impaired driving study, in which they analyzed technology options to test for drug use, including field sobriety tests, according to the Impaired Driving Task Force’s 2021 report.

“In its conclusions, the Task Force’s 2021 report recommended against adopting per se limits for drug impairment due to lack of supporting scientific evidence,” Gieringer wrote in an email to The Bee.

Per se limits make it illegal to drive with specific levels of drugs or alcohol, according to the Stop Drugged Driving website. Washington and Nevada both have per se limits.

In the Task Force’s report, they called for evidence to be collected in a timely manner, recommended laboratories to meet national standards, and voted against adopting per se limits for drug use until there is enough evidence from the scientific community.

“Drugs affect people differently depending on many variables,” the Task Force stated in the report. “A per se limit for drugs, other than ethanol, should not be enacted at this time as current scientific research does not support it.”

California legislators have abstained from adopting per se laws for marijuana DUIs on similar grounds, according to the state’s most recent Impaired Driving Plan published last year.

“The basic problem is that the concentration of THC in bodily fluids does not accurately reflect its activity in brain receptors,” Gieringer said.

Paul Armentano, the deputy director of NORML, said California has laws criminalizing drugged driving behavior that uses an “effect-base” standard where circumstances provide evidence as to whether or not someone was recently exposed to or ingested a drug that influenced their ability to operate a vehicle safely.

“Most states, like California, do not impose so-called per se limits for the presence of cannabis because the detection of these compounds, whether it is in blood, urine, saliva or breath, it is simply not correlated with either psychomotor impairment or cannabis exposure,” Armentano wrote in an email to The Bee.

As an alternative to drug detection-testing, Armentano said NORML has long called for the expanded use of performance-based testing like Druid, which has been shown in clinical studies to be more sensitive and accurate at determining cannabis-induced impairment than Field Sobriety Tests.

Druid is a mobile app that tests drivers for motor and cognitive impairment from any substance including cannabis, according to the app’s creator, Impairment Science.

To better address DUI cannabis behavior, Armentano said he recommends solutions, including having prosecutors move away from drug detection tests toward drug performance tests, using better field sobriety tests that measure cannabis and providing more expansive training for drug recognition experts using validated measures.

What are the penalties for driving while under the influence?

Once a person drives a motor vehicle, California law states they are considered to have given their consent to chemical testing of their blood or breath for the purpose of determining the drug or alcoholic content of their blood.

The CHP website estimates the average cost at approximately $13,500, including insurance hikes, attorney and legal fees, restricted licensing, days off work to go to court and a criminal record.

According to the NORML website, a person can face a fine of $390 to $1,000 for drugged driving and must also complete a DUI program.

Based on the number of drugged driving offenses within 10 years in California, a person can also have the following penalties:

  • First offense: a period of 96 hours to six months in jail and license suspension for six months.

  • Second offense: a period of 90 days to one year in jail and license suspension for two years.

  • Third offense: a period of 120 days to one year in jail, license suspension for three years and an ignition interlock device.

  • Fourth and subsequent offense: imprisonment for a period of 180 days to one year, license suspension for four years and an ignition interlock device.

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