Driving High in the Age of Legal Marijuana

Since recreational marijuana use became legal in California, it is more important than ever that recreational users know their rights when charged with driving under the influence of marijuana. 

On January 1, 2018, the Adult Use of Marijuana Act went into effect in California, legalizing recreational marijuana use for persons 21 and over, along with possession of up to 28.5 grams of marijuana.  But it remains illegal to drive under the influence of any drug, including marijuana.

With punishment for marijuana DUIs at the same level as alcohol-related DUIs, the stakes are high.  A person convicted of a marijuana DUI can face driver’s license suspension, fines, mandatory DUI classes, and jail time. 

No Objective Standard in California for Being Under the Influence of Marijuana

California law does not set a specific amount of THC (tetrahydrocannabinol, the active ingredient in marijuana) that must be in a person’s system for them to be considered impaired by marijuana. This differs from the legal blood alcohol limit of .08% for alcohol-related DUIs.  No such standard exists for marijuana DUIs in California. 

Other states that have legalized marijuana have taken different approaches to marijuana DUIs.  Washington law provides that a person is guilty of a marijuana DUI with a blood THC content of at least 5 nanograms per milliliter.  Colorado has adopted a “permissible inference” rule – the jury is permitted to infer a driver was impaired by marijuana with a blood THC content of 5ng/mL or more, but the driver can still argue they were not impaired.

There is good reason for California to take the approach of not setting a legal THC limit.  There is no scientific consensus on a minimum level of blood THC concentration that can prove impairment.  According to both the National Highway Traffic Safety Administration and the American Automobile Association, studies have not shown a correlation between specific THC levels and an inability to drive safely.

Numerous Obstacles to Proving Marijuana Impairment

Currently, tests for marijuana can only detect the presence of marijuana in your system.  Critically, the marijuana tests CANNOT determine: (1) how much marijuana you consumed or (2) when you last consumed marijuana.  This leads to some defenses that are not always available in alcohol-related DUI cases.

The Driver Used Marijuana But is No Longer High

Even with a positive test for THC in his or her system, a driver can argue at trial that, although they used THC at some point before being stopped, they were no longer under the influence.  Casual users may test positive for marijuana for up to 12 hours after they smoked it.  Frequent users may have positive blood tests even if it has been days since they last smoked or consumed pot.  Urine tests reveal the presence of THC metabolites for even longer – up to four weeks in the case of chronic users. 

The Driver Used Marijuana but Driving Was Not Impaired

Even if a prosecutor can prove the driver recently used marijuana and was under the influence of marijuana, they must also prove the defendant’s driving was impaired.

The 2014 case of a Colorado woman arrested for marijuana DUI, but ultimately found not guilty by a jury, illustrates this point well.  After the woman was pulled over for expired license tags, the officer smelled marijuana and asked her to perform a field sobriety test, which she failed.  After she performed poorly on a separate intoxication test, she was arrested.  Her blood test indicated a blood THC concentration of 18 nanograms per milliliter, more than 3 times the Colorado “permissible inference” level of 5 nanograms.

Despite her high level of blood THC, the jury acquitted the woman on the grounds her driving was not impaired.  She regularly used marijuana to ease the pain of her degenerative disk disease, and her attorney successfully argued that she had not been pulled over for erratic driving or displayed any signs of unsafe driving.

The law and facts can be confusing, but one thing is clear:  California drivers facing marijuana DUI charges need experienced marijuana DUI attorneys to defend their rights. 

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