San Diego DUI Law Center

If you smoke marijuana before driving, can you be prosecuted for DUI in San Diego, attorneys are often asked.  You can be arrested for a San Diego DUI (Drugs) – whether medical marijuana or not – but you cannot be prosecuted for having a minimum amount in your system, lawyers say.

That’s because California law will not change anytime soon for those drivers who toke & drive, as the legislature will not pass a dumb law that says that if you have X amount of nanograms of THC per milliliter in your blood, you are guilty of DUI.

A couple of silly California legislators were at one time proposing a law even stricter than Colorado’s 5 nanograms per milliliter blood-THC standard so that California DUI attorney prosecutors who wanted a slam-dunk easy weapon to discriminate against medical marijuana users who drove.

But it never was a good idea because San Diego drivers would be guilty of DUI regardless of whether they are actually under the influence or impaired while driving which is presently the law.

A recent study to analyze the effects of cannabis on driving performance found that it caused almost no impairment. The impairment that it did cause was similar to that observed under the influence of a legal alcohol limit.  Researchers at the University of Iowa’s National Advanced Driving Simulator carried out the study, sponsored by National Highway Traffic Safety Administration, National Institute of Drug Abuse, and the Office of National Drug Control Policy.

Scientists say they’re having a tough time studying marijuana because under federal law, marijuana is still illegal.   DUI police do not have the equal of a reliable alcohol breathalyzer or blood test so there’s no chemically based way of estimating what the drug is doing in the brain.  A test that can detect some of marijuana’s components does exist, but there is no widely accepted standardized amount in the breath or blood that gives police or courts or anyone else a good sense of who is impaired.

Scientific Reasons why marijuana can not be relied upon in a San Diego DUI prosecution include rational conclusions drawn by a former senior official with the National Highway Traffic Safety Administration, Dr. Jim Hedlund:

“The relations between a drug’s presence in the body, its concentration, measured in blood, breath, saliva or urine, and its impairing effects are complex and not understood well. A drug may be present at low levels without any impairing effects. Some drugs or metabolites may remain in the body for days or weeks, long after any impairment has disappeared (Berning et al., 2015; U.S. Government Accountability Office, 2015).

In particular, marijuana metabolites can be detected in the body for weeks after use (Berning and Smither, 2014).  On the other hand, concentrations in the body of some drugs decrease rapidly while impairing effects persist.  For marijuana, THC concentrations fall to about 60% of their peak within 15 minutes after the end of smoking and to about 20% of their peak 30 minutes after the end of smoking while impairment lasts for 2 to 4 hours (Kelly-Baker, 2014; Logan, 2014).

In addition, individuals differ in how their bodies absorb and metabolize a drug.  In experimental settings, wide ranges of drug concentrations produce similar levels of impairment in different individuals (Berning et al., 2015).

NHTSA’s observation is generally accepted: “At the current time, specific drug concentration levels cannot be reliably equated with a specific degree of driver impairment” (Berning et al., 2015).

Our United States Government Accountability Office agrees: “[I]dentifying a link between impairment and drug concentrations in the body, similar to the 0.08 BAC threshold established for alcohol, is complex and, according to officials from the Society of Forensic Toxicologists, possibly infeasible.”  [“DRUG-IMPAIRED DRIVING – Additional Support Needed for Public Awareness Initiatives,” GAO, February 2015, page 16]

Certainly, Marijuana DUI is tough to prove, although alcohol can change the playing field and may mean a charge including a combination of DUI – alcohol and/or drugs, San Diego DUI attorneys distinguish.

A blood THC DUI limit law would unfairly harm medical marijuana drivers who were otherwise driving unimpaired or with the caution characteristic of a sober person.

The proposed law was also a bad idea to place a blood THC limit on drivers since THC metabolites stay in your blood for days after the marijuana effect wears off.

The bottom line is that marijuana use has increased but accident rates and DUI arrests in California have declined.

The obvious key question is – how was your driving?  Was your driving good or bad?

If charged with DUI – marijuana after being found with some marijuana in your system while speeding or sleeping in the front seat of a parked car, it’s probably not a good idea to plead “no contest” which is the same as guilty.  That’s what rapper and reality TV personality Flavor Fav did in Las Vegas. People without alcohol or drugs speed.  Sleeping is not driving.

Cannabis cruising was the topic for the National College of DUI Defense (NCDD) this year.

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