Traffic Violation Research — Legal & Scientific Analysis
Can You Get a DUI for Caffeine?
Last Verified: June 2026
|Independent Research Report
You drink coffee before every commute. Millions of Americans do. So when you hear that impaired driving laws have been stretched to cover prescription pills, over-the-counter cold medicine, and even cough syrup, a genuinely unsettling question starts to surface: Can you get a DUI for caffeine?
Technically yes — in California, Michigan, Texas, and Florida, broad statutory language is wide enough to charge a caffeine DUI. In practice, no caffeine DUI has ever resulted in a conviction anywhere in the United States. The scientific evidence required to prove that caffeine impaired a driver to an appreciable degree simply does not exist.
That gap between legal theory and prosecutorial reality is where this story gets interesting — and where a California man once spent 16 months fighting a DUI charge for nothing more than the caffeine in his bloodstream. Here is exactly what the law says, what the science says, and why the two are in direct conflict.
Research Summary
The Short Answer: Legally Possible, Practically Unprosecutable
4
States Where Charge Is Possible
California, Michigan, Texas, and Florida have broad "any substance" statutes that technically cover caffeine.
3+
States Where It's Impossible
New York, Ohio, Utah, and Arizona tie DUI exclusively to scheduled controlled substances — caffeine is excluded by law.
0
Successful Convictions, Ever
The only documented caffeine DUI case — Schwab, CA, 2015 — was dropped after 16 months. No conviction exists anywhere in the U.S.
The Statutory Divide: Why Your State Determines Everything
The single most important variable in answering whether caffeine can trigger a DUI charge is not how much caffeine you consumed, how you were driving, or even how a Drug Recognition Expert evaluated you. It is the precise statutory definition of “drug” or “intoxicating substance” in your state's traffic code.
U.S. impaired driving law is not uniform. States fall into two fundamentally different camps, and they produce radically different legal outcomes for the same driver in the same condition. This same broad-versus-narrow statutory divide is what determines the outcome in other unconventional intoxicant cases too — see our companion research on whether cannabis or CBD can trigger a DUI charge for how the same framework plays out with a substance that is far more heavily litigated.
Type 1: Broad “Any Substance” States
These states define a “drug” or “intoxicating substance” by its effect on the driver, not by whether it appears on a controlled substances schedule. If a substance affects the nervous system and impairs driving to an “appreciable degree,” it qualifies — regardless of legal status or societal acceptance.
Examples: California, Michigan, Texas, Florida
Type 2: Narrow Enumerated-List States
These states restrict DUI enforcement to substances explicitly listed in a controlled substances schedule. If caffeine is not on the list — and it isn't, anywhere — no charge can be filed, regardless of how erratically the driver behaved.
Examples: New York, Ohio, Utah, Arizona
How the Key Statutes Are Worded
California
Cal. Veh. Code § 312
Caffeine qualifies
"The term 'drug' means any substance or combination of substances, other than alcohol, which could so affect 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 an ordinarily prudent and cautious man, in full possession of his faculties, using reasonable care, would drive a similar vehicle under like conditions."
"Intoxicated" means not having the normal use of mental or physical faculties by reason of the introduction of alcohol, a controlled substance, a drug, a dangerous drug, a combination of two or more of those substances, or any other substance into the body.
A conviction requires that the driver ingested a drug that is explicitly listed under New York Public Health Law § 3306. That list catalogs scheduled narcotics, opioids, and stimulants like cocaine and amphetamines. Caffeine does not appear.
State-by-State: Can Caffeine Trigger a DUI Charge?
The table below summarizes the key jurisdictions analyzed in our research. The “Yes — Technically” designation means a charge is legally possible under the state's statutory text; it does not mean a prosecution would succeed — in fact, no caffeine prosecution has ever succeeded anywhere.
Caffeine DUI Exposure by State
Verified June 2026 · Primary sources linked
State
Statute
Definition Type
Caffeine DUI?
Key Note
California
Cal. Veh. Code § 312; VC § 23152(f)
Broad / Catch-All
Yes — Technically
Any substance affecting the nervous system that impairs driving to an appreciable degree. The only real caffeine DUI case (Schwab, 2015) collapsed here after 16 months.
Michigan
MCL § 257.625
Broad / Catch-All
Yes — Technically
Intoxicating substance explicitly includes anything recognized as a drug in the U.S. Pharmacopoeia — which lists caffeine.
Texas
Tex. Penal Code § 49.01
Broad / Catch-All
Yes — Technically
Includes "any other substance" — not limited to scheduled drugs. Prosecution still faces the same evidentiary void as California.
Florida
Fla. Stat. § 316.193
Broad / Catch-All
Yes — Technically
"Any chemical substance" impairing normal faculties. No per se caffeine limit; prosecution would rely entirely on officer observations.
New York
N.Y. VTL § 1192(4); Public Health Law § 3306
Narrow / Enumerated
No — Impossible
DUI limited to substances explicitly listed under PHL § 3306. Caffeine is excluded. Courts have reinforced this consistently.
Ohio
Ohio Rev. Code § 4511.19; § 3719.011
Narrow / Enumerated
No — Impossible
"Drug of abuse" restricted to scheduled controlled substances. Caffeine is not scheduled. No per se caffeine limit exists in Ohio law.
Utah
Utah Code § 41-6a-517; § 58-37-101
Narrow / Enumerated
No — Impossible
Metabolite DUI law tied directly to scheduled controlled substances. Caffeine is unscheduled and completely excluded.
The Only Real Case: State vs. Joseph Schwab (California, 2015–2016)
The caffeine DUI is not purely a legal hypothetical. In August 2015, it materialized into the most closely-watched impaired driving case in years — and its outcome became the definitive answer to how prosecutable a caffeine DUI actually is.[8]
Case
Schwab
Solano Co., CA
Arrested: Aug 2015Charges Dropped: Dec 2016Result: No Conviction
Joseph Schwab, 36, was arrested for DUI in Fairfield, California after a California Department of Alcoholic Beverage Control agent observed erratic driving and combative behavior during a traffic stop. His breathalyzer registered 0.00% BAC. A subsequent forensic blood draw — confirmed by a secondary Pennsylvania laboratory — found him completely negative for THC, cocaine, opiates, methamphetamine, benzodiazepines, and all other standard drugs of abuse. The sole psychoactive substance detected was caffeine.
Despite the definitive toxicology results, the Solano County District Attorney pursued the charge for 16 months, arguing that California's Vehicle Code § 312 was broad enough to cover caffeine and that Schwab must have been impaired by something — possibly an undetected designer drug — that their standard screens missed.[8]
The prosecution ultimately collapsed in December 2016. Schwab faced a non-DUI reckless driving charge instead. The case exposed the central problem with any caffeine DUI: forensic toxicologist Jeffrey Zehnder, with 41 years of experience, testified that he had never seen a caffeine impairment case and that no peer-reviewed scientific studies demonstrate caffeine impairs driving to an appreciable degree. He noted that nearly 90% of the global adult population consumes caffeine daily, and the vast majority drive safely while doing so.[8]
The Evidentiary Problem — No Per Se Limit Exists
In an alcohol DUI case, prosecutors rely on decades of peer-reviewed studies proving that a 0.08% BAC correlates directly with degraded reaction time, coordination, and judgment. No equivalent body of evidence exists for caffeine. Without a scientifically established blood concentration threshold tied to measurable driving failure, proving impairment “beyond a reasonable doubt” is essentially impossible — regardless of the statutory language.[8]
How a Caffeine DUI Evaluation Would Actually Work
When a driver is suspected of drug impairment but registers 0.00% on a breathalyzer, law enforcement calls in a certified Drug Recognition Expert (DRE). DREs are trained through the NHTSA-sanctioned Drug Evaluation and Classification (DEC) Program — a rigorous 100+ hour course that teaches officers to identify which of seven drug categories is impairing a driver.[9]
Under the DEC Program, caffeine is officially classified as a Central Nervous System (CNS) Stimulant — the same broad category as cocaine and methamphetamine. If a driver showed symptoms of extreme caffeine intoxication, a DRE conducting the standardized 12-step evaluation would observe a very specific physiological profile.[10]
What a Caffeine-Impaired Driver Looks Like to a DRE
The DRE matrix for CNS stimulants is distinct and would display the following characteristics in a case of extreme caffeine toxicity:
The critical detail: a DRE would identify caffeine as a CNS stimulant based on the physiological signs — elevated pulse, dilated pupils, rigid muscle tone, agitation — but the toxicology report that follows (Step 12 of the evaluation) would return nothing but caffeine. That mismatch — a stimulant presentation with no scheduled drug to match — is precisely the evidentiary dead end that doomed the Schwab prosecution.[10]
The Science: What Caffeine Actually Does at High Doses
To understand why the law even theoretically reaches caffeine, you need to understand what caffeine does to the body at concentrations far beyond a morning cup.
Caffeine is a methylxanthine that acts as a competitive antagonist for adenosine receptors (A1 and A2A) in the brain.[11] By blocking adenosine — the neurotransmitter responsible for fatigue — caffeine artificially maintains wakefulness. The side effect is disinhibition of dopamine and adrenaline systems, triggering a “fight or flight” response: elevated heart rate, higher blood pressure, increased sensory arousal.
In normal, therapeutic doses (3–6 µg/mL in blood, equivalent to a few cups of coffee), this effect is beneficial for driving — reducing lane drift, improving reaction time, and sustaining vigilance.[12] But the dose-response relationship inverts sharply at toxic concentrations:
Caffeine Blood Concentration: Clinical States
Source: Oxford Academic Journal of Analytical Toxicology; NCBI StatPearls [13,14]
Clinical State
Blood Concentration
Expected Symptoms
Therapeutic / Normal
3–6 µg/mL
Alertness, improved reaction time, suppression of fatigue, mood elevation
Severe agitation, tachycardia, hyperreflexia, dilated pupils, confusion, impaired decision-making
Lethal
> 100 µg/mL (mean fatal: ~180 µg/mL)
Cardiac arrhythmia, seizures, pulmonary edema, rhabdomyolysis, death
At toxic concentrations (80–100 µg/mL), the micro-tremors caused by sympathetic overstimulation can interfere with the fine motor control required to steer smoothly, while extreme dopamine-driven emotional agitation can produce aggressive, combative driving behavior — exactly the profile observed in the Schwab stop.[13]
Reaching toxic caffeine levels requires consuming vastly more than a normal diet provides. Concentrated powder supplements, high-dose pre-workout stacks, or intentional abuse are the realistic pathways. A standard cup of coffee contains roughly 80–100 mg of caffeine. The toxic threshold (80 µg/mL in blood) represents a dose that would require extraordinary quantities consumed in a short window.
The Safety Paradox: Caffeine Helps and Harms Driving
What makes the caffeine DUI question uniquely complex is that caffeine occupies both sides of the impairment debate simultaneously.
Moderate Caffeine: A Documented Safety Aid
NHTSA recognizes drowsy driving as a major contributor to fatal crash rates, and controlled research consistently shows that moderate caffeine consumption directly counters driver fatigue.[12] Studies measuring the Standard Deviation of Lateral Position (SDLP) — a metric for lane-keeping consistency — found that one cup of caffeinated coffee improved SDLP scores by an amount comparable to the deficit seen at a 0.05% BAC. In other words, moderate caffeine makes driving measurably safer for tired drivers. Commercial trucking guidelines routinely recommend strategic caffeine use.
Excessive Caffeine: A Documented Risk Factor
A large-scale observational study of over 3,000 commercial truck drivers published in Safety Science found that the high-caffeine group — averaging 7.5 caffeinated drinks per day — was involved in significantly more motor vehicle accidents than the low-caffeine group.[15] The elevated crash risk is attributed to the physiological side effects of CNS overstimulation: severe anxiety, dizziness, tension headaches, and the motor tremors that degrade smooth steering.
The Caffeine Crash: A Hidden Road Hazard
A particularly insidious risk occurs when a caffeine-saturated driver's stimulant finally metabolizes. The adenosine that caffeine was blocking floods the newly unblocked receptors in large quantities — producing a rapid, severe, and often uncontrollable fatigue response.[16] DRE training refers to this as the “downside effect” of stimulants: the driver who was hyperactive and agitated an hour ago is now fighting off micro-sleeps at highway speed with no warning. This caffeine crash — particularly in a driver who is also sleep-deprived — represents a genuine, documented road safety hazard.
The Masking Effect: Why Caffeine + Alcohol Is Especially Dangerous
Research shows that caffeine can partially mask the subjective sedative effects of alcohol — making an intoxicated person feel falsely alert. Caffeine does not reverse the cognitive impairment, coordination deficits, or judgment failures caused by alcohol. The result is a driver who feels sober enough to drive but whose actual faculties are still significantly impaired. In DUI casework, elevated caffeine alongside alcohol or prescription depressants often signals a driver who actively tried to counteract their own intoxication.[17]
Frequently Asked Questions
Can you actually get a DUI for drinking too much coffee?
In theory, a charge could be filed in states like California, Michigan, Texas, or Florida. In practice, no successful prosecution has ever occurred. The evidentiary standard — proving that caffeine impaired your driving to an "appreciable degree" beyond a reasonable doubt — has never been met, because the scientific literature to support that conclusion does not exist.
What was the outcome of the California caffeine DUI case?
Joseph Schwab was arrested in August 2015 in Fairfield, California after a blood test found caffeine as the only substance in his system. The Solano County District Attorney pursued DUI charges for 16 months. The charges were dropped in December 2016 — no conviction was obtained. Schwab ultimately faced a non-DUI reckless driving charge.
Is caffeine classified as a drug under DUI law?
It depends on the state. In California (VC § 312), Michigan (MCL § 257.625), and Texas (Penal Code § 49.01), the statutory definition of "drug" or "intoxicating substance" is broad enough to include caffeine. In New York, Ohio, Utah, and Arizona, DUI statutes are tied to specific controlled substance schedules that exclude caffeine entirely.
What amount of caffeine would actually impair driving?
Normal therapeutic blood levels (3–6 µg/mL) actually improve driving for fatigued drivers. The physiological symptoms associated with driving impairment — tremors, extreme agitation, tachycardia — appear at toxic levels of approximately 80–100 µg/mL. Reaching that concentration requires consuming extraordinary quantities far beyond typical daily intake. No per se legal limit for caffeine exists in any U.S. jurisdiction.
Can the caffeine crash impair driving?
Yes, and this is one of the more legitimate safety concerns. When high doses of caffeine wear off — especially in a sleep-deprived driver — the sudden release of accumulated adenosine can produce rapid, uncontrollable fatigue. DRE protocols call this the "downside effect" of stimulants. A driver experiencing a severe caffeine crash may be genuinely unable to operate a vehicle safely due to sudden drowsiness and micro-sleeps.
Does caffeine cancel out alcohol impairment?
No. Research shows caffeine can partially mask the subjective feeling of alcohol intoxication — making a drunk person feel more alert — but it does not reverse the cognitive deficits, coordination failures, or poor judgment caused by alcohol. Mixing caffeine with alcohol creates a dangerous scenario where drivers underestimate their own impairment.
Legal Disclaimer
This content is provided for informational and educational research purposes only. It does not constitute legal advice and does not create an attorney-client relationship. Laws are subject to change; verify current statutes with your state's official code or consult a qualified attorney in your jurisdiction before taking any action.
Primary Source Directory
California Vehicle Code § 312 — Definition of “Drug”: California Legislative Information — Defines “drug” as any substance affecting the nervous system that impairs driving to an appreciable degree. The foundational text for California caffeine DUI theory.
New York Vehicle and Traffic Law § 1192(4) / Public Health Law § 3306: New York State Legislature — DWAI-Drug statute requires the ingested substance to appear on the PHL § 3306 controlled substances list. Caffeine is excluded, making a caffeine DUI charge legally impossible in New York.
Michigan Compiled Laws § 257.625 — Operating While Intoxicated: Michigan Legislature — Includes intoxicating substances recognized as drugs in the U.S. Pharmacopoeia, which lists caffeine. Foundation for Michigan caffeine OWI theory.
Florida Statute § 316.193 — Driving Under the Influence: Florida Legislature — DUI statute covers “any chemical substance” that impairs normal faculties, providing the statutory basis for a theoretical caffeine charge.
Ohio Revised Code § 4511.19 / § 3719.011 — OVI and Drug of Abuse Definitions: Ohio Legislature — “Drug of abuse” restricted to scheduled controlled substances; no per se caffeine limit. Makes a pure caffeine OVI effectively impossible in Ohio.
State v. Schwab — Solano County, California (2015–2016): The only documented caffeine DUI case in U.S. history. Charges dropped December 2016 after 16 months of prosecution. Reported by The Guardian and Seattle DUI Attorney Aaron Wolff; toxicology expert testimony sourced from Jeffrey Zehnder, 41-year forensic toxicologist.
NHTSA — Advanced Roadside Impaired Driving Enforcement (ARIDE) Participant Guide (2023): National Highway Traffic Safety Administration — Official training documentation for the Drug Evaluation and Classification (DEC) Program. Caffeine classified as a CNS Stimulant.
NHTSA / IACP — DRE 7-Day Student Manual (DEC Program): National Highway Traffic Safety Administration / International Association of Chiefs of Police — Documents the 12-step DRE evaluation protocol and the CNS stimulant physiological indicator matrix.
Mechanisms of the Psychostimulant Effects of Caffeine — PMC: PubMed Central (PMC4846529) — Peer-reviewed analysis of caffeine's adenosine receptor antagonism and dopamine/adrenaline disinhibition mechanisms.
Effects of Coffee on Driving Performance During Prolonged Simulated Highway Driving — PMC: PubMed Central (PMC3382640) — Documents measurable improvements in lane-keeping (SDLP) from moderate caffeine use; basis for NHTSA anti-drowsy-driving guidance.
Caffeine Toxicity — StatPearls / NCBI Bookshelf: National Center for Biotechnology Information — Clinical reference on caffeine toxicity symptoms, blood concentration thresholds, and physiological effects.
Use of Caffeinated Substances and Risk of Crashes in Long Distance Drivers — The BMJ: British Medical Journal — Case-control study of 3,000+ commercial truck drivers linking high caffeine consumption (≈7.5 drinks/day) to elevated crash rates.
NHTSA — Drug Recognition Expert 7-Day Student Manual HS 172 R1/07 (Maine.gov): National Highway Traffic Safety Administration — Documents the “downside effect” and “negative feedback” protocol for DRE evaluations of stimulant comedown states.
Caffeine in Forensic Toxicology: A Comprehensive Review — MDPI: MDPI Forensic Sciences — Documents caffeine's masking effect on alcohol impairment and its role in poly-drug DUI casework.