9 Things You Should Know About Marijuana DUI

VC 23152(f)

If you have been arrested for Marijuana DUI you should be aware that blood THC level is not a reliable indicator of impairment1.

Below are 9 things you should know about Marijuana DUI’s in California.

Overview of Marijuana Laws

Marijuana is a controlled substance and is legal to possess in California beginning January 1st, 2018 after the passage of proposition 64.

Driving while under the influence of marijuana, however, is unlawful whether you legally ingested it or smoked it.

Under California Vehicle Code 23152(f) VC, you can be arrested and charged for driving under the influence of drugs if the drug impaired your mental abilities so as to render you unable to drive with the caution of a sober person using ordinary care under similar circumstances2.

Effects Of Marijuana

Marijuana is the most popular illicit drug used in the US. This is based on its containing a substance called delta-9-tetrahydrocannabinol (THC)

When smoked, the drug passes quickly from the lungs to the bloodstream and then to the brain and other organs. Besides giving you a “high,” other effects can include:

  • Drowsiness
  • Memory impairment
  • Altered sense of time
  • Increased appetite
  • Mood changes

Marijuana use and its effects vary among users. However some studies show that most Marijuana intoxicated drivers show only modest if any impairment under the influence of Marijuana3.

Proof Of Impairment

There is no objective test for impairment from marijuana or what level, if any, you may be presumed to be under the influence4.

For alcohol consumption, however, the blood alcohol concentration (BAC) limit at which you are presumed legally intoxicated for driving purposes is 0.08%.

This is a “per se” violation so that a finding of 0.08% is an automatic violation5.

Under California law, there is no “per se” violation of any statute, meaning there is no level of delta-9-tetrahydrocannabinol (THC), the active ingredient in cannabis, which is considered illegal or for which the law presumes you are under the influence or impaired.

Implied Consent

All motorists in California are obligated to submit to chemical testing of their blood alcohol level if the arresting officer has probable cause to believe you were driving while under the influence of alcohol or drugs. If you refuse testing, then the prosecutor can use your refusal to argue at trial that you refused because you were under the influence6.

A refusal is also an aggravating factor with the following adverse consequences:

Testing Methods

Whether marijuana impairs your ability to drive is not a matter of general consensus and detection of the drug in your system is not necessarily indicative of impairment. If you used marijuana on a regular basis and then stopped, the THC can remain in your system for up to 30 days.

Still, you can be charged and convicted based upon other evidence that you were driving impaired, which may include:

Driving conduct that may exhibit impairment are weaving within lanes, failing to stop at a stop sign or red traffic signal, swerving, driving too slowly, being asleep in your car at the side of the road and causing an accident.

To determine if a drug is the cause of your alleged impairment, there are law enforcement officers called Drug Recognition Experts or DREs who are trained to look for certain signs. These may include:

  • Dilated pupils
  • Rapid breathing
  • Rapid heart rate
  • Red eyes
  • Odor of marijuana

If the officer feels there is probable cause to believe you are impaired, then you will be asked to submit to a breath or blood test7. If you do choose the breath test and it is negative for alcohol, the officer has the right to ask that you take a blood test if the officer reasonably believes you used a drug8.

By detecting marijuana in your system, the prosecutor can argue that your demeanor, attitude, conduct and odor of the drug among other factors is enough to show that you were under its influence.

The tests used to detect marijuana in your system include the following:

Blood Test

A blood or breath test may detect the presence of THC in your system but it is more significant for what such a test does not reveal:

A blood or breath test may detect the presence of THC in your system but it is more significant for what such a test does not reveal:

  • Unlike alcohol, the test cannot reveal when you used the drug or at least within a few hours
  • It is not a reliable test of how much you ingested or smoked
  • There is no consensus on how much marijuana in your system indicates you are impaired when driving

The high from marijuana use occurs shortly after using it and can last for a few hours. If you used it 4 or 5 hours previously, you are likely no longer under its influence so that it would appreciably affect your driving behavior.

Because marijuana is fat-soluable, it remains in your body for hours or days after use depending on whether you are chronic or occasional user. If used occasionally, it can remain for 12 hours. If you are a chronic user, it can last from 2 to 30 days.

Urine Test

A urine test may be requested if you are a hemophiliac or otherwise cannot have blood drawn. However, urine tests for marijuana are considered even less reliable than blood tests. These do not check for the presence of delta-9-tetrahydrocannabinol or THC but for inactive metabolites such as THC carboxylic acid. This substances can remain in your body for 30 days, long after you experienced its psychoactive effects.

A urine test can also detect the presence of THC-cannibidiol, which is a non-psychoactive substance found in the drug. These substances are in some strains of marijuana that are used for medical purposes.

Because it can remain in your body for days, you might be suspected of driving while under the influence of marijuana if the arresting officer believed you were based on driving conduct, odor of marijuana in your car or some remnants of a marijuana cigarette found in your car.

Saliva Test

There are also saliva tests that have been used in other countries, like Australia, but getting a test on the roadside is not as easy or as effective as it is at a lab since saliva has enzymes that break down molecules so that samples will degrade before they get to a lab for testing.

Currently, results of a saliva test is not admissible in court and is only used by an officer on the scene to make inquiries, similar to use of a PAS or preliminary alcohol screening test9.

Effects Of Marijuana On Driving Behavior

There are studies that indicate that marijuana use does impair driving10 while others are inconclusive. If driving after having smoked or ingested marijuana, research tends to show that it may double the risk of causing an accident11.

Alcohol consumption on the other hand increases the risk by 20 times in some groups.

Further research also showed that drivers high on pot drove slower or more cautiously than those who drank alcohol who tend to speed, drive erratically and are less focused on driving12.

Legal Defenses For Marijuana DUI

The defenses to marijuana DUI may include any of the following:

You Were Not Impaired

Merely because a blood, urine or saliva test revealed the presence of marijuana in your system is not evidence of impairment.  THC can be detectable for up to 12 hours after ingestion or inhalation, long after its effects have dissipated. As indicated, a urine test that shows THC metabolites in your system only means that you could have last smoked up to a month ago.

Although the DA can use the presence of THC in your system and argue that you showed signs of impairment based on your FST performance or other evidence, a good defense attorney can show that perfectly legal factors other than drugs or alcohol accounted for this erroneous conclusion.

Flawed Testing

A suspected motorist’s performance on a field sobriety test (FST) is often used as evidence of impairment. These many consist of finger to nose test, walking a straight line, one leg stand or walking and turning. Any number of reasons can explain your poor performance including fatigue and extreme stress and anxiety since you are being accused of a serious offense and your conduct is being closely observed.

Another FST is the horizontal gaze nystagmus test where you are instructed to follow the officer’s finger as it moves from side to side. The officer is looking for involuntary jerking of your eye or movement or eye jerking at or before a 45 degree angle. This allegedly indicates a high level of intoxication. This is a subjective test that should need correlation with other credible evidence.

Also, blood, urine and saliva tests are not without flaws. The technician who draws your blood or urine and labels it or preserves it must be trained and certified13. Also, these tests do not demonstrate when you smoked or ingested the drug.

Additional Defenses: See 8 DUI drug defenses that can get your charges reduced or dismissed.


The penalties and sentencing for driving while under the influence of marijuana are the same as for a DUI. It is generally charged as a misdemeanor. For a first offender, you can expect:

  • 96 hours in jail up to 6 months
  • Fine of $390 to a maximum of $1000
  • Driver’s license suspension of 6 months
  • Summary or informal probation of 3 to 5 years
  • Participation in a DUI or drug education class for 3-months

The penalties increase with each subsequent Marijuana DUI conviction with mandatory minimum jail sentences imposed.

There are circumstances where a Marijuana DUI is elevated to a felony. If you cause an accident with serious bodily injuries or death or have a fourth DUI, DUI of Drugs or “wet reckless” conviction, or any combination, within 10 years, or have a DUI because of a prior felony DUI conviction, then the DA can charge you with a felony with the following potential sentence:

  • 180 days in county jail
  • 4-year license suspension
  • Probation for up to 5 years
  • Participation in an 18-month alcohol or drug education class
  • Fine up to $5000
  • Restitution to victims if involved in an accident

Expungement For Marijuana DUI

You can seek post-conviction relief by obtaining an expungement of your conviction under California Vehicle Code 23152(f) by petitioning the court pursuant to Penal Code 1203.4. By expunging your conviction, you can state under oath that you have not been convicted of that offense.

Your expunged conviction will also not appear on any pubic record databases so that any landlords or private employers will see no criminal convictions on your record. This is the most significant benefit of an expungement.

  • Find Out if You Are Eligible To Have Your Record Expunged
  • Stop Worrying About Employer Background Checks
  • Stop Worrying About Landlord Background Checks

Eligibility for Expungement

Most Marijuana DUI or DUID convictions are misdemeanors and are eligible for expungement. The criteria for eligibility includes the following:

  • You served no time in state prison
  • You completed all terms and conditions of your probation
  • You did not commit a subsequent felony
  • No criminal charges are pending

A felony Marijuana DUI might be eligible for expungement but only if you did not serve time in state prison. In most marijuana DUI felony cases, you would serve your time in county jail unless some aggravating factor prompted the judge to sentence you to state prison.

If you were convicted of felony marijuana DUI, you can petition the court to reduce it to a misdemeanor before having it expunged under PC 17(b)(3) since it is a “wobbler” offense, meaning the DA could still have charged you with a misdemeanor instead.

Since you have to wait until your probation has been served, you can ask the court to reduce your probation under PC 1203.4 so you can request an expungement sooner.

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  1. Marijuana Impaired Driving – A Report to Congress. NHTSA []
  2. Vehicle Code 23152(f) – It is unlawful for a person who is under the influence of any drug to drive a vehicle., available at https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=23152 []
  3. The effect of cannabis compared to alcohol – National Institutes Of Health []
  4. See Also Drug & Human Performance Fact Sheet – NHTSA []
  5. Peretto v. Department of Motor Vehicles (1991) 235 Cal.App.3d 449, 459-460 []
  6. People v. Sudduth (1966)  65 Cal.2d 543, 547 []
  7. People v. Macknic (1967) 257 Cal.App.2d 370 []
  8. People v. McGinnis (1953) 123 Cal.App.2d Supp. 945 []
  9. See Also Marijuana Swab Testing Los Angeles Times []
  10. See National Institutes Of Health Meta-Analysis []
  11. See., Marijuana Use & Vehicle Crashes []
  12. See., The influence of Cannabis on Driving []
  13. People v. Williams (2002) 28 Cal.4th 408, 417 []

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