Driving under the Influence of Marijuana
California Vehicle Code 23152(f)

 

Recreational use of marijuana (cannabis) has been legal in California since January 1, 2018.

But driving under the influence of marijuana is a still a crime in California. 1 Penalties for DUIs involving cannabis are summarized in the following chart:

DUI offense

(drugs and/or alcohol)

Possible penalties

1st DUI

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 jail; $390-$1,000 fine; 18 or 30 months DUI school; 2 years suspended license (convertible to 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

The crime of DUI of marijuana is set forth in California Vehicle Code 23152(f). VC 23152(f) provides:

“It is unlawful for a person who is under the influence of any drug to drive a vehicle.” 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

police next to car during marijuana dui inquiry
Being in the driver's seat is not enough to prove that you drove for purposes of California's DUI of marijuana law.

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 does the prosecutor prove that someone drove under the influence of cannabis?

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

male blowing into breathalyzer during marijuana dui stop
Unlike alcohol, there is no “legal limit” for marijuana under California law.

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 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;
  • 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.

lab technician holding blood test for marijuana dui
If drug use is suspected in a DUI, a driver may be required to take a blood test.

3. Which chemical test will a driver have to take after an arrest for VC 23152(f)?

When someone is arresting 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 (e.g., 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.

marijuana dui urine sample in vial held by scientist
Urine tests can show that someone recently used marijuana, but not how much.

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 “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.

oral swab being administered during marijuana dui test
Some California counties have begun using a roadside “oral fluid” (saliva) test for marijuana

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:

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.

suspended california license dui to marijuana dui
A 6-month driver's license suspension is a standard penalty for a first VC 23152(f) conviction.

8. The penalties for DUI of marijuana

Penalties for DUI of marijuana are the same as for driving under the influence of alcohol. Unless a serious accident is involved, it is usually charged as a misdemeanor.

But if someone is seriously injured, VC 23152(f) becomes a California “wobbler” offense. A “wobbler” can be charged as either a misdemeanor or a felony, in the prosecutor's discretion.

8.1. Misdemeanor punishment for VC 23152(f)

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:

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:

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 (e.g., 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.

a canister holding marijuana spilling bud onto a prescription
Needing medical marijuana is not a legal excuse for driving under its influence in California.

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 points out:

“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 VC 23152(f) 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 even a little from the use of marijuana, the driver can be found guilty under VC 23152(f).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, VC 23152(f):

10.1. Driving in possession of marijuana -- Vehicle Code 23222

Driving with an open container of marijuana in the car is generally illegally 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…

marijuana dui defense attorney receptionist smiling
Call us at 855-LAWFIRM for help

If you have been arrested and charged with VC 23152(f), we invite you to contact our California DUI defense lawyers for a free consultation.

Call us at 855-LAWFIRM or fill out the form on this page to speak to a knowledgeable DUI defense lawyer in your area.

We have local offices 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:

  1. California Vehicle Code 231f2(f).
  2. See also California Vehicle Code 23152 (g): “It is unlawful for a person who is under the combined influence of any alcoholic beverage and drug to drive a vehicle.”
  3. CALCRIM 2110: “[A drug is a substance or combination of substances, other than alcohol, that could so affect the nervous system, brain, or muscles of a person that it would appreciably impair his or her ability to drive as an ordinarily cautious person, in full possession of his or her faculties and using reasonable care, would drive under similar circumstances.

    See also Health and Safety Code 11054(d)(13). Health and Safety Code 11054 is part of California's “Uniform Controlled Substances Act.” Under HS 11054(d)(13), cannabis (marijuana) is classified as a Schedule 1 hallucinogen.

  4. CALCRIM 2110.
  5. See People v. Wilson (1985) 176 Cal. App. 3d Supp. 1 (“[W]e conclude that a reasonable person would construe the phrase ‘to drive a vehicle' in subdivision (a) of section 23152 of the Vehicle Code as encompassing any act or action which is necessary to operate the mechanism and controls and direct the course of a motor vehicle.”).
  6. See People v. McGinnis (1953) 123 Cal.App.2d Supp. 945, 267 P.2d 458 (holding that the guilt of an accused in DUI cases may be established by circumstantial as well as by direct evidence, and that the right to draw proper inferences from the evidence is a function of the jury).
  7. Facts adapted from People v. Wilson, endnote 5 (“From the combination of circumstances--defendant's sitting in a vehicle in the center of the street--behind the wheel--engine running--lights on, it can be inferred that defendant must have placed himself in such position, and that he accomplished this by driving the car to the place at which he was found.”)
  8. People v. Wilson, endnote 5.
  9. See, e.g., Mercer v. Department of Motor Vehicles (1991) 280 Cal. Rptr. 745, 53 Cal. 3d 753, 809 P.2d 404 (“Based on (i) the ‘plain meaning' of the statutory term ‘drive,' (ii) the use of that and related terms by our Legislature in related statutes, and (iii) the interpretation of the word ‘drive' and related terms in numerous decisions by our sister states, we conclude section 23152 requires proof of volitional movement of a vehicle.”)
  10. CALCRIM 2110 (“A person is under the influence if, as a result of (drinking [or consuming] an alcoholic beverage/ [and/or] taking a drug), his or her mental or physical abilities are so impaired that he or she is no longer able to drive a vehicle with the caution of a sober person, using ordinary care, under similar circumstances.”).

    See also People v. Enriquez (1996) 42 Cal.App.4th 661, 49 Cal.Rptr.2d 710 (“To be 'under the influence' within the meaning of the Vehicle Code, the ... drug(s) must have so far affected the nervous system, the brain, or muscles as to impair to an appreciable degree the ability to operate a vehicle in a manner like that of an ordinarily prudent and cautious person in full possession of his faculties.”)

  11. DUI of alcohol can be charged under VC 23152(a) if the prosecutor proves that someone's driving was impaired by alcohol, regardless of blood alcohol content (“BAC). But DUI can also be charged under VC 23152(b) when a driver's BAC is .08 or greater, even if his/her driving is not actually impaired. This is known as a DUI “per se.” Another (less accurate) way to put this is that the “legal limit” for alcohol in California is .08 %. There is no equivalent “per se” limit for marijuana.
  12. See, e.g., KQED News, “How Much Marijuana Is Too Much to Drive?”, December 21, 2017.
  13. For instance, Washington state law specifies that adult drivers are considered DUI if they have five nanograms of more of active tetrahydrocannabinol (THC) in their blood. Revised Code of Washington (RCW) 46.61.502(1)(b).
  14. Centers for Disease Control and Prevention, “What is marijuana?”; See also Ziva D. Cooper and Margaret Haney, “Actions of delta-9-tetrahydrocannabinol in cannabis,” Journal

    International Review of Psychiatry, Volume 21, 2009 - Issue 2.

  15. See, e.g., WebMD, “As CBD Oil Flirts with Mainstream, Questions Mount,” June 5, 2018.
  16. See National Institute on Drug Abuse, “Effects of marijuana – with and without alcohol – on driving performance,” June 23, 2015.
  17. People v. Macknic (1967) 257 Cal.App.2d 370, 64 Cal.Rptr. 833 (holding that detailed testimony by an expert as to the defendant's observable physical and mental reactive state was sufficient to prove that defendant was “under the influence” of a narcotic drug).
  18. People v. McGinnis, endnote 6.
  19. See, e.g., People v. Weathington (1991) 231 Cal.App.3d 69, 282 Cal.Rptr. 170 (“If the issue is whether the ability of the driver to operate his vehicle is impaired, the manner in which the vehicle is driven is evidence which tends to prove or disprove that fact.”). The Weathington court also found there was substantial evidence of impaired driving due to the defendant's slurred speech, swaying, staggering walk, and statements regarding his consumption of alcohol.

    See also WebMD, “How Does Marijuana Affect You?”

  20. See, e.g., Los Angeles Police Department, “The Evolution of the DRE Officer and Program.”
  21. Vehicle Code 23612(a)(2)(B): "If the person is lawfully arrested for driving under the influence of any drug or the combined influence of an alcoholic beverage and any drug, the person has the choice of whether the test shall be of his or her blood or breath, and the officer shall advise the person that he or she has that choice."
  22. Vehicle Code 23612(a)(2)(C): “A person who chooses to submit to a breath test may also be requested to submit to a blood test if the officer has reasonable cause to believe that the person was driving under the influence of a drug or the combined influence of an alcoholic beverage and a drug and if the officer has a clear indication that a blood test will reveal evidence of the person being under the influence. The officer shall state in his or her report the facts upon which that belief and that clear indication are based. The officer shall advise the person that he or she is required to submit to an additional test. The person shall submit to and complete a blood test. If the person arrested is incapable of completing the blood test, the person shall submit to and complete a urine test.”
  23. Same.
  24. NPR, “Scientists Still Seek A Reliable DUI Test For Marijuana,” July 30, 2017.
  25. Same.
  26. “Marijuana-Impaired Driving: A Report to Congress,” National Highway Safety Traffic Administration, pp. 5-6.
  27. Same, pp. 4-5.
  28. Same, p. 7.
  29. An example of such metabolites is THC carboxylic acid (THC-COOH). See e.g., Jason C. Laberge and Nicholas J. War, “Research Note: Cannabis and Driving — Research Needs and Issues for Transportation Policy,” The Journal of Drug Issues (2004).
  30. Same.
  31. Same.
  32. See, e.g., WebMD, “As CBD Oil Flirts with Mainstream, Questions Mount,” June 5, 2018.
  33. See Los Angeles Times, “Police are using new mouth-swab tests to nab drivers under the influence of marijuana and other drugs,” March 17, 2017.
  34. Marilyn A. Huestis and Michael L. Smith, “Cannabinoid Markers in Biological Fluids and Tissues: Revealing Intake,” December 2017.
  35. See “Scientists Still Seek A Reliable DUI Test For Marijuana,” endnote 24.
  36. See Vehicle Code 23612(a)(1)(B): "A person who drives a motor vehicle is deemed to have given his or her consent to chemical testing of his or her blood for the purpose of determining the drug content of his or her blood, if lawfully arrested for an offense allegedly committed in violation of Section 23140, 23152, or 23153. If a blood test is unavailable, the person shall be deemed to have given his or her consent to chemical testing of his or her urine and shall submit to a urine test."
  37. Same.
  38. See Vehicle Code 13353 VC.
  39. See Vehicle Code 13353 VC.
  40. People v. Macknic, endnote 17.
  41. WebMD, endnote 32.
  42. “Marijuana-Impaired Driving, a Report to Congress,” endnote 26, p. 7.
  43. Maggie Koerth-Baker, “Driving Under the Influence, of Marijuana,” NYTimes.com, Feb. 17, 2014.
  44. See, e.g., Vehicle Code 23536 VC [penalties for a first violation of VC 23152].
  45. Vehicle Code 23153: “…(e)It is unlawful for a person, while under the influence of any drug, to drive a vehicle and concurrently do any act forbidden by law, or neglect any duty imposed by law in driving the vehicle, which act or neglect proximately causes bodily injury to any person other than the driver. (f) It is unlawful for a person, while under the combined influence of any alcoholic beverage and drug, to drive a vehicle and concurrently do any act forbidden by law, or neglect any duty imposed by law in driving the vehicle, which act or neglect proximately causes bodily injury to any person other than the driver…"
  46. Vehicle Code 23513 VC.
  47. Vehicle Code 23554 VC: “If any person is convicted of a first violation of Section 23153 [DUI causing injury], that person shall be punished by imprisonment in the state prison, or in a county jail for not less than 90 days nor more than one year, and by a fine of not less than three hundred ninety dollars ($390) nor more than one thousand dollars ($1,000). The person's privilege to operate a motor vehicle shall be suspended by the Department of Motor Vehicles pursuant to paragraph (2) of subdivision (a) of Section 13352. The court shall require the person to surrender the driver's license to the court in accordance with Section 13550.”

    See also Vehicle Code 13352(a)(2): “Upon a conviction or finding of a violation of Section 23153 punishable under Section 23554, the privilege shall be suspended for a period of one year…”

  48. Penal Code 187 PC.
  49. Vehicle Code 23152(g), endnote 2.
  50. See, e.g., Wyeth Pharmaceuticals' prescribing information for Protonix: “5.11 Interference with Urine Screen for THC. There have been reports of false-positive urine screening tests for tetrahydrocannabinol (THC) in patients receiving PPIs, including PROTONIX.”
  51. “Marijuana-Impaired Driving, a Report to Congress,” endnote 26.
  52. Same.
  53. See Vehicle Code 23152(b).
  54. See e.g., People v. Torres (2009)173 Cal.App.4th 977, 93 Cal.Rptr.3d 303 (holding that the potential of methamphetamine to impair driving was insufficient to convict defendant of DUI drugs [and by extension DUI of marijuana] absent expert evidence showing that his drug use actually affected his driving ability).
  55. Santa Ana criminal and DUI defense lawyer John Murray is one of Southern California's leading experts on DUI criminal defense. He has considerable expertise on the law governing driving and marijuana use as well as a proven track record of success at DMV hearing locations throughout southern California, including those in the City of Commerce, Covina, El Segundo, Oxnard, San Bernardino, and Van Nuys.
  56. Vehicle Code 23152(c) VC.
  57. CALCRIM 2110: “[It is not a defense that the defendant was legally entitled to use the drug.]”
  58. Same: “[If the defendant was under the influence of (an alcoholic beverage/[and/or] a drug), then it is not a defense that something else also impaired (his/her) ability to drive.”
  59. Vehicle Code 23222(b)(1): “Except as authorized by law, every person who has in his or her possession on his or her person, while driving a motor vehicle upon a highway or on lands, as described in subdivision (b) of Section 23220, any receptacle containing any cannabis or cannabis products, as defined by Section 11018.1 of the Health and Safety Code, which has been opened or has a seal broken, or loose cannabis flower not in a container, is guilty of an infraction punishable by a fine of not more than one hundred dollars ($100).”
  60. Health and Safety Code 11357(a).
  61. Health and Safety Code 11357(b)(2).
  62. Health and Safety Code 11357(b)(1).

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