Should California Have a Legal Limit for DUI of Marijuana?

Posted by Jon Ibanez on March 23rd, 2018

Prop. 64 is in full swing here in California. While medicinal marijuana has been legal in California since 1996, recreational marijuana is now available for adults who are at least 21-years-old, subject to certain limitations. Up to an ounce of marijuana can be purchased per day and consumed in private locations. The private location cannot, however, be in a vehicle whether you are the driver or the passenger. More importantly for us, a person still cannot drive while under the influence of marijuana.

To be legally under the influence of marijuana a person’s mental or physical abilities are impaired to a degree that they can no longer drive a vehicle with the caution of a sober person, using ordinary care, under similar circumstance.

This definition of impairment is the same for a DUI of alcohol as well. However, with a DUI of alcohol, a person need not be under the influence as long as they have a blood alcohol content of at least 0.08 percent at the time of driving. The purpose behind this rule is that science has established a strong correlation between a blood alcohol content of 0.08 percent or higher and the definition of impairment spelled out above.

Alcohol, which is water-soluble, is absorbed and eliminated from the body relatively quickly. In most circumstances, if a person consumes alcohol during an evening of drinking, the alcohol should be eliminated by the following morning.

The same, however, cannot be said of marijuana. When someone consumes marijuana, the “high” comes from tetrahydrocannabinol (THC) and can last several hours. THC is fat-soluble and can stay in a person’s system for weeks, possibly longer, even though the “high” has long since worn off. As such, there’s little to no correlation between the amount of THC in a person’s system and whether they meet the definition of being under the influence stated above.

Notwithstanding the lack of a correlation between the amount of THC in a person’s system and degree of impairment, Washington State, which has also legalized recreational marijuana, set a limit of 5 nanograms of THC per milliliter of blood in a person’s system.

Lt. Rob Sharpe, who works for the Washington State Patrol’s impaired driving unit, told the Los Angeles Times he believes establishing a legal limit for pot is a necessity.

“If I don’t know how much marijuana I can consume and safely drive, how can I be held to a standard that it’s unsafe to drive?” he asked.

The problem with Washington’s “per se” limit is that a regular user of marijuana can have 5 nanograms of THC per milliliter of blood weeks after having consumed marijuana.

It doesn’t take a lawyer or a judge to tell you that the purpose of DUI laws, whether they’re for DUI of alcohol or DUI of marijuana, is to protect the driver and the public as a whole from impaired driving because that is what’s dangerous. And now that marijuana is legal in both California and Washington, as well as a number of other states, it is no different than alcohol. Like alcohol, a person should be free to consume something that they are legally allowed to consume without fear of being arrested for a DUI days or weeks later.

To have a per se limit for THC, as Washington does, would allow law enforcement to arrest someone for a DUI of marijuana weeks after they have consumed marijuana even though they are no longer impaired. It would be the same as if law enforcement arrested someone for a DUI of alcohol weeks after a night of drinking when they haven’t had a drop of alcohol since that night.

Should there be a per se legal limit for marijuana? Absolutely not, at least not until science can determine how impaired someone is when they’ve consumed marijuana.

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