Checking for Marijuana DUI

Checking for Marijuana DUI

Checking for Marijuana DUI

When being pulled over for a Marijuana “DUI”, there are no established tells of impairment as there are with an alcohol DUI.

If you get pulled over for a “Marijuana DUI” you should know there’s no established way to tell when a driver is impaired by marijuana.

Measuring Marijuana Impairment

Alcohol impairment is extremely easy to measure. When pulled over and suspected of alcohol impairment, you will be put through a field sobriety test, which includes breathing into a Breathalyzer. This will measure the level of alcohol in your blood. There is no such technology that measures marijuana influence. Marijuana is especially hard to test for because it stays in your blood and urine for weeks, making it impossible to determine when it was consumed.

So how does law enforcement test for THC impairment?

Marijuana Field Sobriety Test

If an officer suspects that a driver is under the influence of Marijuana, they will conduct a field sobriety test. This includes a series of exercises that are more difficult to execute when under the influence, the most standard being “horizontal gaze nystagmus test”, the “walk and turn test”, and the “one-leg stand.”

Horizontal Gaze Nystagmus Test

This test, commonly refereed to as the “eye follow” test, is administered by taking an object and moving it side to side in front of a person’s face to see if they are able to follow the object. This test is used to detect any involuntary jerking of the eyes. The eye jerks naturally at a 45 degree strain. If it jerks before that point, it may be a sign of influence and can be referenced as evidence. The National Highway Traffic and Safety Administration (NHTSA) estimates this test is 77% reliable.

Walt and Turn Test

This test is designed to engage the suspect both physically and mentally at the same time. By asking them to walk in a straight line, the officer can watch for the following evidence of inebriation:

  • Loss of balance
  • Wrong number of steps
  • Inability to stay on the line
  • Breaks in walking
  • Beginning before instructed

NHTSA estimates that this test is effective 68% of the time.

One Leg Stand Test

This test is another way to divide someone’s physical and mental attention by asking them to raise a hand and foot and hold it while they look down and count.  An officer may arrest the suspect if any of the following behaviors are observed:

  • Swaying
  • Hopping
  • Putting foot down

NHTSA estimates that this test is effective 65% of the time.

Additional Tests

If an officer has enough evidence to believe that someone is driving under the influence, the will be required to take a blood, breath or urine test under California’s “implied consent” law which requires all drivers lawfully arrested for a DUI to submit to chemical testing to determine either blood alcohol concentration (BAC) or the amount of drugs in the person’s system.

A blood and breath test is more common than a urine test, and the driver is usually able to choose the type of test they take. As stated above, using blood, breath, or urine tests to trace marijuana within a certain time frame can be inaccurate and misleading because of the way marijuana reacts in the system. THC is held in your body’s fat, so you can still test positively up to two weeks – or even longer – after using it.

Saliva Drug Swab Test

There is now a third method of testing that involves taking a saliva sample to detect THC, crystal meth, methadone, cocaine, and several other prescription medications.

This is a newer test and the accuracy is still unclear. It works by detecting trace amounts of drugs in the suspect’s saliva, which can last up to three days depending on the drug.

Lawful Arrest

In order for an arrest to be lawful and held up in court, there must be probable cause that the suspect was driving under the influence of drugs or alcohol.

The officer must read the Miranda Rights at the time of the arrest. An arresting officer is required by law to explain the consequences of refusing any of the above test methods. If you do not subject to a test, you’ll be fined, lose your license, and face jail time if convicted of a DUI.

Driving Illegally in California

When driving in California, the following is considered illegal:

  • Drivers under the age of 21 are prohibited from transporting or carrying unsealed wine, liquor, or beer, in their vehicle if they are driving alone. Exceptions are if it is work-related.
  • Drivers under the age of 21 are prohibited from driving with a blood alcohol concentration (“BAC”) of 0.01 or higher.
  • Drivers under the age of 21 are prohibited from consuming any form of alcohol, including prescription drugs or cough syrup.
  • Any driver or any age is prohibited from driving with a BAC of 0.08 or higher. A BAC of 0.08 is the standard measurement all states use in order to establish whether a driver is impaired.
  • The driver of any vehicle requiring a commercial driver’s license is prohibited from driving with a BAC of 0.04 or higher.
  • A driver under the age of 18 is prohibited from driving with ANY measurable BAC.
  • Repeat offenders are prohibited from driving with a BAC of 0.01 or higher.

Although these laws are specific to California, the same DUI laws are similar in states throughout the United States.


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