Driving Under the Influence of Marijuana or Drugs

Also referred to as DUI drugs or drugged driving, driving under the influence of marijuana or drugs -- or any combination -- is a crime. In California, it is an offense that commonly has the same consequences as driving under the influence of alcohol. Vehicle Code section 23152a, the specific law that discusses driving under the influence of drugs or marijuana states:


The legal definition for the phrase under the influence is actually identical to driving under the influence of alcohol:

Affecting the nervous system, brain, or muscles of a person as to impair, to an appreciable degree, his ability to drive a vehicle in the manner that any ordinarily prudent and cautious man, in full possession of his faculties, using reasonable care, would drive a similar vehicle under like conditions.

One place where these two offenses differ is in the consequences. When a suspect is charged with driving under the influence of alcohol, there is the so-called per se offense (having a blood-alcohol concentration, or BAC, at or above .08%; Vehicle Code section 23152b). When charged with driving under the influence of marijuana or driving under the influence of drugs, however, there is no blood-alcohol level (or if it is under .08%) and therefore no per se offense to charge the suspect with. Because of this, the DMV cannot administratively suspend the suspect's license for driving under the influence of drugs or marijuana. This suspension is only administered when the suspect refused chemical testing or there is a BAC above .08%. As part of a criminal conviction, however, the license can still be suspended.

There are also a few differences between the two crimes in how chemical testing is administered. Where the standard test given to DUI suspects is the breath test, a breath test will not register the presence of marijuana or drugs. Therefore, if the officer suspects the individual was driving under the influence of marijuana or drugs, a blood test will be administered. A times, a urine test may be used.

NOTE: The legal use of marijuana is not a defense to driving under the influence of marijuana. A driver may be legally using the drug, such as with a physician’s prescription, but if he is legally impaired by its use, he can be convicted — just as a driver who has legally used alcohol can be convicted of DUI alcohol.

Aside from the blood test, evidence presented by the prosecution for a DUI drugs or DUI marijuana case will also include the comments from the arresting officer (much like in a DUI alcohol case):

The indicators for alcohol intoxication are much different than those of drug or marijuana intoxication, which often poses a problem. The officer making the arrest is often not qualified and/or not trained to identify drug symptomology. If this is the case, the defense has the power to stop the officer from testifying. However, an increasing number of cases are calling another officer who has this skill to examine the individual in question. Also known as a drug recognition expert, or DRE, this officer is trained specifically to identify the symptoms of numerous drugs, including marijuana. A qualified DRE can testify to the symptoms of drugs and/or marijuana, and the resulting impairments.

An important fact to note: the issue is not the legal status of the drug in use, but the impairment it may cause on the driver. Drugged driving cases do not always involve dangerous illegal drugs or narcotics. The drugs used by the suspect could be over-the-counter products (Nyquill or Benadryl, for example) or legally prescribed medicines. The attention is on the driver's mental stability and physical capabilities. See ‘‘ How Legal Drug Use Can Lead to a DUI or DWI’’.

There are many complications in proving the crime of driving under the influence of drugs . Mostly due to a lack of scientific research, the prosecution for these crimes is still a new development. Science is still unable to:

  1. Compare the amount of drugs to the amount of impairment caused by them
  2. Identify individual tolerance to particular drugs, including marijuana

Because of these shortages, the prosecution still faces some problems. If a DRE does not examine the suspect, for example, the prosecution will be unable to determine how the observed symptoms are associated with which drug or marijuana. Also, if a blood test is taken, the analysis may be unable to identify which drug was used. If the results do show a particular drug though, it might not be able to prove if enough of the drug or marijuana was taken to mentally and physically impair the driver passed the legal limit.

For a discussion of the research on the effects of marijuana on driving, see "Marijuana and Driving: a research brief from the University of Washington". For an interesting article in the Washington Post, see “ Stoned Drivers Are a Lot Safer than Drunk Ones, New Federal Data Show".

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