DUI of Marijuana – Laws, Penalties & Defenses

DUI of marijuana is the criminal offense of operating a motor vehicle when your driving ability is impaired from being under the influence of marijuana. While the recreational use of marijuana is now legal in a number of states, including California, DUI of marijuana remains a crime across the United States.

In California, the penalties for DUI of marijuana are virtually identical to DUI of alcohol. However, unlike alcohol, with marijuana, there is no “per se” limit as to the concentration a motorist can have in his or her blood. And there is a lingering controversy about whether and to what extent marijuana impairs a person’s driving ability. This allows for more opportunities for defense attorneys to challenge a DUI marijuana charge in court.

The penalties for DUIs involving cannabis in California are summarized in the following chart:

DUI charge (drugs and/or alcohol)	Possible penalties
1st DUI	Up to 6 months jail; $390-$1,000 fine; 3 or 9 months DUI school; 6 – 10 months suspended license (convertible to restricted license).
2nd DUI	96 hours – 1-year of jail time; $390-$1,000 fine; 18 or 30 months DUI school; 2 years suspended license (convertible to a restricted license after 12 months).
3rd DUI	120 days – 1 year jail; $390-$1,000 fine; 30 months DUI school; 3 years revoked license (restricted license possible after 18 months).
Misdemeanor DUI w/injury	5 days – 1-year jail; $390-5,000 fine (plus restitution to injured parties); 3, 18 or 30 months DUI school; 1 – 3 years revoked license.
Felony DUI	16 months, 2 years or 3 years state prison; $390-$1,000 fine; 18 or 30 months DUI school; 4 years revoked license.
Felony DUI w/injury	16 mos.-16 yrs. state prison; $1,015-5,000 fine (plus restitution to injured parties); 18 or 30 mos. DUI school; 5 years revoked license.

To help you better understand Vehicle Code 23152(f), our California DUI defense lawyers discuss the following, below:

• 1. The legal definition of DUI of marijuana in California
  • 1.1. The legal definition of “driving” a vehicle
  • 1.2. The legal definition of “under the influence” of marijuana
• 2. How can the state prove a DUI of marijuana charge?
• 3. Which chemical test will a driver have to take?
• 4. How reliable are chemical tests for marijuana?
  • 4.1. Blood tests
  • 4.2. Urine tests
  • 4.3. Oral swabs / saliva tests
• 5. Can a driver refuse to take a DUI chemical test for marijuana?
• 6. Must a driver be offered a chemical test?
• 7. Does marijuana impair driving ability?
• 8. The penalties for DUI of marijuana
  • 8.1. Misdemeanor punishment
  • 8.2. Felony punishment for DUI of marijuana
• 9. Legal defenses to DUI of marijuana
  • 9.1. The driver has not used marijuana
  • 9.2. The driver recently used marijuana, but is no longer high
  • 9.3. The driver used marijuana but his/her driving was not impaired
  • 9.4 Legal marijuana use is not a defense to DUI marijuana
  • 9.5. No defense that impairment was based partly on other causes
• 10. Related offenses to DUI marijuana
  • 10.1. Driving in possession of marijuana — Vehicle Code 23222
  • 10.2. Unlawful possession of marijuana for personal use

1. The legal definition of DUI of marijuana in California

The crime of driving under the influence of marijuana is set forth in California Vehicle Code 23152(f). This section states:

“It is unlawful for a person who is under the influence of any drug to drive a vehicle.” ^{1 2}

A person violates this law when:

1. He or she drives a vehicle; and
2. He or she is under the influence of any drug (including cannabis);³ and
3. His or her mental or physical abilities are so impaired by such drug(s) that he/she is unable to operate the vehicle with the caution of a sober person, using ordinary care, under similar circumstances.⁴

Let’s take a closer look at some of these elements.

1.1. The legal definition of “driving” a vehicle

For purposes of California DUI law, the word “drive” carries its usual, everyday meaning.⁵

Proving that the defendant drove is usually fairly easy for the prosecution. This is because a typical arrest for DUI of cannabis occurs during a traffic stop.

But an officer can also arrest someone for DUI even if he/she did not see that person drive. The prosecution may then prove that person drove from circumstantial evidence.⁶

Example: A California Highway Patrol officer comes across a car parked at an angle on the shoulder of a highway. The rear part of the car is sticking out into one of the lanes. All the car’s lights are on. The engine is running.

The car has one occupant, Darryl. Darryl is sitting behind the wheel, asleep. He smells of marijuana. There is also a baggie of weed and a bong on the front passenger seat.

Even though the officer did not see Darryl drive the car, she can arrest him. The car could only have gotten onto the shoulder if someone had driven it there. And a jury could reasonably conclude that (1) Darryl was the one who had driven the car, and (2) he had done so recently and while stoned.⁷

Being behind the wheel of a vehicle is not enough

Even though circumstantial evidence can be proof of driving, merely sitting behind the wheel of a car is not enough – even with the engine running.

A person only drives under California law when:

1. He or she intentionally performs some action, and
2. Such action is one that is necessary to operate and direct the course of a motor vehicle.⁸

Example: An LAPD officer sees Alfred smoke a joint outside of a bar.  Afterwards, Alfred gets into the driver’s side of his car and turns on the ignition.  The officer immediately arrests him for DUI marijuana.

But since Alfred never actually drove the vehicle – and there was no reason to believe he had driven the vehicle while stoned — there is no probable cause for a DUI arrest.⁹ He could have been sitting in the running vehicle simply to get warm or to listen to the radio.

1.2. The legal definition of “under the influence” of marijuana

A driver is “under the influence” of marijuana when:

1. As a result of consuming cannabis,
2. His or her mental or physical abilities are so impaired,
3. That he/she is unable to drive a vehicle with the caution of a sober person, using ordinary care, under similar circumstances.¹⁰

Whether a defendant was under the influence is an issue to be decided by a “trier of fact.” The trier of fact can be:

• A jury, or
• If the defendant prefers, a judge (in a California “bench” trial).

The jury or judge will decide whether the prosecutor has proved beyond a reasonable doubt that the defendant drove under the influence of marijuana.

2. How can the state prove a DUI of marijuana charge?

Proving DUI of marijuana presents serious challenges for a prosecutor. This is because, unlike alcohol, ¹¹ there is no “legal limit” for marijuana under California law.¹²

In this respect, California is different from some other states. Some states restrict the amount of THC that can be in a driver’s bloodstream.¹³

THC (short for “delta-9-tetrahydrocannabinol”) is the main psychoactive ingredient in marijuana.¹⁴ It is what makes users feel “stoned” or “high.”

Some strains of weed are low in THC and high in a substance known as “cannabidiol” (“CBD”). CBD is a non-psychoactive substance found in marijuana.

Many medical marijuana users choose high CBD strains so as to obtain the health benefits of cannabis without getting high. ¹⁵

Chemical tests for cannabis are not reliable

Some of the reasons why California has no legal limit for THC include that:

1. Chemical tests for THC are not yet reliable enough, and
2. Experts cannot agree on how much marijuana is too much for driving.¹⁶

We discuss these issues at length in Sections 4 and 5, below. But in short, a chemical test alone is usually not sufficient to convict someone of DUI of marijuana.

A driver can be convicted without a chemical test

Chemical test results are not necessary to convict a driver of DUI of marijuana.¹⁷ They are just one piece of evidence the prosecutor can use to show impaired driving. ¹⁸

This means a prosecutor can charge someone with driving under the influence even if he or she is not offered, or he or she refuses to take, a chemical test.

What other evidence can be used to convict someone of DUI of cannabis?

In addition to (or instead of) chemical test results, evidence of driving under the influence of marijuana may include:

• The defendant’s driving pattern;
• The defendant’s statements to the police officer;
• The defendant’s performance on Field Sobriety Tests (FSTs);
• The presence of marijuana or drug paraphernalia in the defendant’s car or on the defendant’s person;
• Physical symptoms of intoxication, such as:
  • Dilated pupils,
  • Rapid heart rate,
  • Rapid breathing,
  • The odor of marijuana coming from the defendant’s body,
  • Red eyes,
  • Dry “cotton” mouth, and/or
  • Slowed reaction time; and/or
• Evidence showing that the defendant is addicted to marijuana. ¹⁹

Drug recognition experts

Most of the evidence of impairment will be established through testimony from the arresting officer. But some California law enforcement agencies also employ a “Drug Recognition Expert” (DRE).

In these jurisdictions, the arresting officer will often call for a DRE when drug use is suspected in a DUI case.²⁰ The DRE will examine the defendant and may testify at trial about the defendant’s physical symptoms of impairment.

3. Which chemical test will a driver have to take?

When someone is arrested for driving under the influence, he/she must be offered the choice of either a DUI breath test or a DUI blood test.²¹

Most drivers choose a breath test, which is less invasive than a blood test.

But if drug use is suspected, a driver may be required to take a blood test, even if he/she initially chose a breath test. This additional test may only be requested, however, only if the officer reasonably believes that:

• The driver is under the influence of marijuana or other drugs, and
• A blood test will reveal the presence of drugs.²²

This typically happens in the following situations:

• A breath test comes up negative, or low, for alcohol, and/or
• The officer smelled marijuana on the driver, and/or
• The officer observed physical signs of intoxication, and/or
• The officer found drugs and/or drug paraphernalia in the driver’s car.

Note that if the driver cannot take a blood test because of a medical condition (such as hemophilia) – or if blood testing is not available – the driver may take a urine test instead. ²³

4. How reliable are chemical tests for marijuana?

There are three basic problems with using chemical tests to prove that someone drove under the influence of marijuana:

1. Chemical tests don’t indicate reliably when cannabis was used;
2. They don’t indicate reliably how much was used; and
3. There is no consensus on how much marijuana leads to impaired driving.²⁴

Test results can also vary depending on which type of test is used.

Let’s take a quick look at the problems associated with blood, urine and saliva tests for marijuana.

4.1. Blood tests

The most commonly used chemical test in a DUI of marijuana case is a blood test. Blood tests look directly for the presence of delta-9-tetrahydrocannabinol (“THC”).

But unlike alcohol, THC is not metabolized at a steady rate, especially when it is smoked. Instead, the level of THC in the blood can peak in as little as ten minutes, after which it declines rapidly.²⁵

By the time someone has been arrested and a blood sample has been taken, most (but not all) of the THC is gone.²⁶

THC is detectable for up to a month after marijuana use

The bigger problem with a blood test for THC is that unlike alcohol, which is water-soluble, THC is fat-soluble. This means that once ingested, it is stored in the body’s fatty tissues.

These fatty tissues can leach stored THC back into the blood for up to one month or longer. So a blood test for THC can be positive even if a driver has not recently smoked or consumed marijuana. ²⁷

What is more, low THC levels in the blood can result either from:

• Relatively recent use (for example, smoking within the prior 1 – 3 hours), or
• Chronic use (even without any recent ingestion).²⁸

So a positive blood test doesn’t mean much in the context of a possible VC 23152 violation.

Example: Alice smokes marijuana three or four times a week. One day she runs a stop sign and is pulled over. The officer smells pot on Alice’s clothes and arrests her.

Ironically, this happens on a day when Alice has not used cannabis and is not high. But because she is a habitual user, her blood test turns up positive for THC.

4.2. Urine tests

A urine test does not check directly for the presence of THC. Instead, it detects the presence of inactive metabolites that are found in marijuana.²⁹

These inactive metabolites can be detected in urine long after marijuana use. Some estimates suggest they can be detected for up to four weeks in chronic users.³⁰

And since these substances do not themselves cause impairment, a positive urine test does not prove that someone was “under the influence” of marijuana. It merely indicates that the person consumed cannabis at some point within the last month or so.³¹

High CBD / low THC strains are prone to false positives

High CBD/low THC marijuana is particularly susceptible to misleading urine test results.³² This is because even though this type of cannabis does not get people high, it still contains cannabis metabolites other than THC. These metabolites can trigger a “false positive” result on a DUI urine test.

Example: Adam suffers from a blood-clotting disorder and frequent migraines. He sometimes smokes high-CBD marijuana in the evenings to help him manage his headache pain.

One morning on his way to work, Adam accidentally runs a red light. An officer pulls him over and smells marijuana on Adam’s clothes. She arrests him for driving under the influence. After his breath test proves negative for alcohol, Adam is ordered to take a blood test to screen for drugs.

Because of his clotting disorder, Adam is allowed to take a urine test instead. So even though Adam isn’t high, his urine shows the presence of marijuana metabolites. As a result he is charged with violating Vehicle Code 23152(f) VC.

4.3. Oral swabs / saliva tests

Some California counties have begun using a roadside “oral fluid” (saliva) test for marijuana.³³ The test is performed by swabbing the insides of the suspect’s mouth with a cotton swab.

Such swabs are relatively non-invasive. They can also narrow the window of marijuana use to a few hours. ³⁴

But while saliva tests are good at detecting the presence of marijuana, they are not reliable indicators of how much was consumed or whether a driver was impaired.³⁵

Saliva tests have also not yet been ruled admissible in driving under the influence cases.

So at present, law enforcement agencies that use saliva tests do so as a preliminary screening test only. If a driver’s saliva tests positive for THC, the officer will most likely then arrest the driver and require a blood test.

5. Can a driver refuse to take a DUI chemical test for marijuana?

Drivers in California are deemed to have consented to a chemical test for alcohol and/or drugs if they are lawfully arrested for DUI. This is known as California’s “implied consent” law. ³⁶

But it is important to distinguish between a pre-arrest roadside test, such as a saliva swab or, and A post-arrest DUI chemical test of the driver’s blood or urine.

For instance, during a traffic stop or at a DUI checkpoint, an officer may ask the driver to:

• Blow into a hand-held Breathalyzer for a preliminary alcohol screening (PAS) test,
• Submit to a saliva swab to test for marijuana and/or other drugs, and/or
• Perform one or more field sobriety tests (such as the “one-leg stand” test).

As long as the driver has not yet been placed under arrest, he/she may legally decline to take all these tests.³⁷ No magic words are required.

Penalties for refusing a post-arrest chemical test

Once someone has been lawfully arrested for DUI, refusal to take a chemical test has consequences. These include an automatic one-year suspension of the driver’s license – even if the driver is not charged with, or is later found “not guilty” of, driving under the influence. ³⁸

Other consequences of a chemical test refusal include increased penalties if the driver is later convicted of DUI. For a first-time conviction these enhanced penalties can include:

• Two extra days in jail, and
• Nine months of California DUI school, instead of the usual three-month program.³⁹

What if the arrest was not lawful?

People who think their arrest is unlawful do not need to argue it with the officer in order to preserve their rights. They can take a chemical test and let their California DUI attorney fight the legality of the arrest later.

If the arrest turns out to be unlawful, the test results will be thrown out – even if they show that the driver used marijuana.

And if it was a lawful arrest, there is still no need to panic.  A positive chemical test does not, by itself, prove that a driver was under the influence of marijuana at the time he or she drove.

6. Must a driver be offered a chemical test?

Police are not required to offer a driver a chemical test. This is important because, as we discussed above, THC and other marijuana metabolites remain in the blood and urine for a long time. So a negative chemical test is a strong indication that the driver did not use marijuana.

A driver who wants such exculpatory evidence must affirmatively request a chemical test. The police must allow the driver to take one provided that the driver is willing to pay for the test at his/her own expense. ⁴⁰

7. Does marijuana impair driving ability?

The effect of marijuana on driving ability is a subject for debate.

Part of the problem is that marijuana is still classified as a Schedule 1 narcotic under the federal Controlled Substances Act. This has resulted in a lack of research on the effects of THC on driving.

What is known for a fact is that THC can produce alterations in motor behavior, perception, cognition, and memory.⁴¹  But so far, studies have not shown a consistent correlation between THC use and driver impairment.

In fact, in some studies, drivers have been least impaired when THC concentration in the blood is at its highest. And some drivers have shown more significant impairment when their THC levels were low.⁴²

This may simply be because drivers tend to drive more cautiously after significant marijuana use.⁴³

But whatever the reason, the upshot is that chemical tests do not prove beyond a reasonable doubt that someone’s driving was actually impaired by marijuana.

8. The penalties for DUI of marijuana

Penalties for DUI of marijuana are the same as for an alcohol DUI. Unless a serious accident is involved, it is usually charged as a misdemeanor. (It does not matter whether the driver used medicinal or recreational marijuana.)

But if someone is seriously injured, the offense becomes a California “wobbler” offense. A “wobbler” can be charged as either a misdemeanor or a felony, at the prosecutor’s discretion.

8.1. Misdemeanor punishment

As a first offense, punishment for any DUI conviction (including DUI of marijuana) can include:

• Informal (summary) probation for three (3) to five (5) years,
• Between 96 hours and six months in county jail,
• A fine of between $390 and $1,000, and/or
• A six-month driver’s license suspension. ⁴⁴

These penalties increase slightly for a second or third conviction.

8.2. Felony punishment for DUI of marijuana

In rare cases, DUI of marijuana can be charged as a felony. This can occur if:

• An accident due to cannabis use results in injury (or death) to a third party, ⁴⁵ or
• The driver has three or more prior DUI or wet reckless convictions within the last 10 years, or
• The driver has even one prior felony conviction within the 10 preceding years.⁴⁶

Felony penalties for driving under the influence can include:

• Felony (formal) probation, and/or
• A California state prison sentence, and/or
• A one-year or longer suspension of the driver’s license.⁴⁷

And if a third party dies due to a defendant’s impaired driving, the defendant could conceivably be charged with:

• Gross vehicular manslaughter while intoxicated, Penal Code 191.5(a) PC, or even
• Second-degree murder – known as “Watson” murder or DUI murder.⁴⁸

9. Legal defenses to DUI of marijuana

Many legal defenses to driving under the influence of alcohol can also be used to fight DUI marijuana charges. Common legal defenses include taking the position that:

• The driver did not drive (“no driving” defense),
• The DUI traffic stop and/or arrest was unlawful, and/or
• The police failed to conduct a chemical test in accordance with California Title 17 regulations.

But a few defenses are special to charges of DUI marijuana (or driving under the combined influence of marijuana and alcohol).⁴⁹

Let’s take a brief look at each of these defenses.

9.1. The driver has not used marijuana

Marijuana’s metabolites are fairly unique. As a result, it is unlikely that a driver will test positive for marijuana if he/she has not used it within the last month or so.

A negative chemical test result is, therefore, usually a good indication that the driver is not guilty of DUI of marijuana.

But even a “positive” result can sometimes be inaccurate. Reasons for such inaccuracy include:

• Flaws with the chemical test procedures or equipment, or
• Certain medications, such as proton pump inhibitors (for example, Protonix) for gastrointestinal reflux disease.⁵⁰

Drivers should tell their California DUI lawyer about ALL drugs and supplements they use – whether prescription, over-the-counter, or illegal.

9.2. The driver recently used marijuana, but is no longer high

Chemical tests can show whether someone used marijuana, but not how long ago it was consumed.

Occasional users may test positive for marijuana for up to 12 hours after smoking it.  People who use it more frequently may test positive for THC even if it has been days since they last smoked or consumed weed.⁵¹

And chronic users may test positive for a month or more after using marijuana – even if they have stopped using it completely.⁵²

This is why prosecutors in DUI marijuana cases can’t rely on chemical tests as “smoking guns.” A good DUI defense lawyer will make this clear to the prosecutor and – if the DUI of marijuana case goes to trial – to the judge or jury.

9.3. The driver used marijuana but his/her driving was not impaired

Even if the prosecutor can prove the driver recently used marijuana, it does not mean the driver will be convicted.

The California legislature has not set a “per se” blood THC limit, such as the maximum .08% limit it has set for blood alcohol content (BAC).⁵³ This means that the prosecutor must prove beyond a reasonable doubt that the driver was actually impaired when he or she drove.⁵⁴

As Santa Ana criminal and DUI defense lawyer John Murray⁵⁵ explains:

“No one agrees exactly how much THC in the blood makes a driver ‘impaired.’ The burden is on the prosecutor to prove that someone’s drug use actually affected his or her ability to drive safely. With marijuana especially, that can be difficult to do.”

Driving while addicted is a crime

It is important to note that it is a crime in California to drive while addicted to any drug (including marijuana).⁵⁶ Addicted driving is considered a form of California DUI and carries the same penalties.

Prosecutors rarely charge people with driving while addicted to a drug. But a zealous prosecutor who can’t prove a driver was impaired might try instead to prove the driver was addicted to marijuana.

9.4 Legal marijuana use is not a defense to DUI marijuana

It is not a defense to DUI drug charges that the driver had the legal right to use marijuana. This is true even if the driver was using the drug under California’s medical marijuana laws.⁵⁷

If a drug impairs driving, it doesn’t matter whether it was legally or even medically necessary. If someone’s ability to drive safely is impaired, he or she may not lawfully drive.

9.5. No defense that impairment was based partly on other causes

It is also not a defense to the charges that impairment was caused in part by something other than marijuana.

For example, perhaps someone was using marijuana to treat a migraine and the migraine was the main cause for the impairment.

If the impairment resulted in even a little from the use of marijuana, the driver can be found guilty.⁵⁸

But the prosecutor must still prove that the driver was actually impaired.

10. Related offenses to DUI marijuana

People arrested for driving under the influence of cannabis are often charged with the following offenses in addition to, or instead of, DUI:

10.1. Driving in possession of marijuana — Vehicle Code 23222

Driving with an open container of marijuana in the car is generally illegal in California. It is prohibited by Vehicle Code 23222(b), California’s law on “driving in possession of marijuana.” ⁵⁹

This law does not apply, however, to open containers of weed in the trunk of the vehicle.

Violation of VC 23222(b) is an infraction. It can be punished by a fine of up to $100.

10.2. Unlawful possession of marijuana for personal use

Effective January 1, 2018, adults age 21 and over may lawfully possess the following quantity of marijuana in California:

• Up to 28.5 grams of flowers, stems, seeds, etc., or
• Up to eight grams of concentrated cannabis (hashish).⁶⁰

Possession of marijuana in more than this amount is a misdemeanor for anyone age 18 or older. It can be punished by:

• Up to six (6) months in county jail, and/or
• Up to five hundred dollars ($500) in fines.⁶¹

Possession of smaller quantities by people aged 18-20 – or possession of any quantity by someone under 18 – is an infraction. Depending on the person’s age and the amount possessed, it can be punished by:

• A fine of up to $100,
• Mandatory drug education or counseling, and/or
• Mandatory community service.⁶²

Charged with DUI of marijuana in California? Call us for help…

If you have been arrested, we invite you to contact our California DUI defense attorneys for a free consultation.

Call us or fill out the form on this page to speak to a knowledgeable criminal defense attorney in your area.

We create attorney-client relationships throughout California, including Los Angeles, the San Fernando Valley, Pasadena, Long Beach, Orange County, Ventura, San Bernardino, Rancho Cucamonga, Riverside, San Diego, Sacramento, Oakland, San Francisco, and San Jose.

We also have offices in Las Vegas and Reno that can help people charged with DUI of marijuana in Nevada.

Legal references: