Marijuana DUI Cases: Why Toxicology Evidence Matters
Article overview: The Track Record: We literally never lose marijuana/THC cases at trial. We’ve taken every marijuana DUI case to trial in 20 California counties, with only one loss that was subsequently overturned on appeal. In Napa County alone, we secured six consecutive full acquittals, with juries returning…
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The Track Record: We literally never lose marijuana/THC cases at trial. We’ve taken every marijuana DUI case to trial in 20 California counties, with only one loss that was subsequently overturned on appeal. In Napa County alone, we secured six consecutive full acquittals, with juries returning instant not-guilty verdicts. This led to a wave of dismissals.
Recent Victory: Vista, CA Case Just in a minute ago.
Defense Team: Juanita Kay and Mauro Quintero
Client: 26-year-old female, no prior criminal history
Venue: Vista, CA (North San Diego County)
Case Facts
Client admitted to THC use the night before a tragic accident where her vehicle struck and killed a motorist whose car had broken down. Blood toxicology revealed 5ng of THC.
Charges Filed
- Count 1: PC 191.59 Gross Vehicular Manslaughter while intoxicated with gross negligence (15-year maximum sentence)
- Count 2: VC 23153 DUI Causing Injury (8-year maximum sentence)
- Count 3: PC 192(c)(1) Vehicular manslaughter with gross negligence (felony, reducible to misdemeanor)
Trial Results
Kay and Quintero systematically dismantled the prosecution’s THC impairment case:
- Count 1: NOT GUILTY
- Count 2: NOT GUILTY
- Count 3: GUILTY (expected to be reduced to misdemeanor under PC 17(b))
Strategic Win: Neutralizing the “Hired Gun” Attack
The prosecutor’s planned cross-examination strategy centered on portraying me as a “hired gun” expert witness. When asked about compensation, I responded: “I haven’t seen the court order, but I understand the maximum is $2,000.”
This reference to court-appointed compensation immediately prompted the prosecutor to request sidebar (one that lasted longer than my testimony or felt like it. It was long) and “pitch a fit” –as he knew we were completely derailing his planned attack and exposing the weakness of his case to the jury.
The Lesson Reinforced
This Vista victory, combined with our undefeated record across 20 counties, even Colusa County, proves that marijuana DUI cases are fundamentally different from alcohol DUI prosecutions. Juries consistently reject THC impairment theories when properly challenged, regardless of venue.
The science simply isn’t there. Unlike alcohol cases with established correlations between blood alcohol content and impairment, THC cases rely on flawed assumptions that experienced defense teams can systematically dismantle.
OO’s Golden Rule: Do NOT plead to a DUI based on a THC level.
Why marijuana DUI cases turn on science
A positive cannabis result does not automatically prove impairment at the time of driving. THC concentrations change rapidly, inactive metabolites may persist, tolerance varies and no single universal number converts a laboratory finding into reliable proof of driving performance.
Continue with the analysis of drug levels and impairment.
Related reading: For related context, read Court Filing Accuses Judge Rupert Byrdsong of Prejudicial Misconduct and Siding With the Defense, Filed Declarations Accuse Judge Rupert Byrdsong of Harassment, Interference and Retaliation. Browse the Forensic Toxicology topic hub.
