Alcohol Effects on the Body
Understanding what alcohol actually does to a customer's brain and body is the foundation of refusing service before that customer becomes a §25602 problem. The legal Blood Alcohol Concentration (BAC) limit for driving is 0.08% under Vehicle Code §23152(b) — and 0.04% for commercial drivers (§23152(d)), 0.01% for drivers under 21 (§23136), 0.04% for ride-share/TNC drivers — and your job as a server is to keep customers from getting there at your bar.
How alcohol enters and leaves the body
Alcohol — ethanol, the same chemical in beer, wine, and spirits — is absorbed quickly through the stomach (about 20 percent) and small intestine (about 80 percent), reaching the bloodstream within minutes. Food in the stomach slows absorption but does not block it; carbonation (in a vodka soda or champagne) speeds absorption by moving alcohol into the small intestine faster. The liver metabolizes alcohol at a roughly fixed rate of about 0.015 BAC per hour for most adults — about one standard drink per hour. There is no shortcut: coffee does not sober anyone up, cold showers do not, food after drinking does not, and 'walking it off' does not. The only thing that lowers BAC is time. A standard drink in California is defined as 12 oz of 5% beer, 5 oz of 12% wine, or 1.5 oz of 80-proof spirits — each contains about 0.6 oz of pure ethanol. A craft beer at 8% ABV is not one drink, it is closer to one and a half; a 22-oz bomber of that beer is closer to three. A 'long pour' margarita is often two drinks in one glass. Training your eye to count actual standard drinks, not glasses, is the foundation of recognizing impairment before it shows.
Factors that change how alcohol affects each customer
Two customers, same drinks, very different impairment. The variables matter for service: body weight (a 120-lb person reaches a higher BAC from the same drink than a 200-lb person), biological sex (women generally have less alcohol dehydrogenase in the stomach and higher body-fat percentage, so they reach higher BAC from the same drink), age (older customers metabolize more slowly and are more sensitive at the same BAC), food in the stomach (slows absorption but does not prevent intoxication), rate of drinking (chugging puts more alcohol into the bloodstream than the liver can clear), carbonation and warmth of the drink (faster absorption), medications and other drugs (prescription opioids, benzodiazepines, antihistamines, marijuana — all amplify impairment), fatigue and dehydration (amplify subjective impairment and reduce judgment), and tolerance (chronic heavy drinkers may not look drunk at a BAC that would have anyone else under the table — but their driving and judgment are still impaired and §25602 still applies to them). A customer who is a 'high-functioning alcoholic' is exactly the customer §25602 was written about; the obviously intoxicated standard is behavioral, not BAC-based.
Stages of impairment and what to watch for
Impairment progresses along a recognizable curve, and a trained server learns the early signs before they become liability. Stage 1, sub-clinical (BAC 0.01-0.05): customer feels relaxed, slightly more talkative, mild euphoria — usually no service problem. Stage 2, euphoria (BAC 0.03-0.12): louder, more outgoing, lowered inhibition, beginning loss of fine motor coordination, slightly impaired judgment — this is the slow-down zone, where you offer water and food. Stage 3, excitement (BAC 0.09-0.25): emotional swings, slurred speech, reduced reaction time, blurred vision, balance starts to go — this is the obviously intoxicated zone and §25602 service must stop. Stage 4, confusion (BAC 0.18-0.30): disoriented, severe motor impairment, may not know where they are — arrange a safe ride and do not let them leave with car keys. Stage 5, stupor (BAC 0.25-0.40): may pass out, may vomit, risk of aspiration; call 911 — alcohol poisoning is a medical emergency. Stage 6, coma (BAC 0.35+): unresponsive, risk of death from respiratory depression — call 911 immediately. The legal driving limit of 0.08 sits inside Stage 3 — and at 0.08, the customer is already legally obviously intoxicated under §25602.
Long-term consequences and customer health context
RBS training is mostly about the next hour, but understanding the longer arc helps a server connect with a regular customer who is heading toward harm. Chronic heavy drinking causes liver disease (fatty liver, alcoholic hepatitis, cirrhosis), pancreatitis, multiple cancers (mouth, throat, esophagus, liver, colon, breast), heart disease and high blood pressure, brain shrinkage and cognitive decline, depression and anxiety, and alcohol-use disorder. Fetal Alcohol Spectrum Disorder is the consequence of drinking during pregnancy and is fully preventable — BPC §25612.5 requires the pregnancy-warning sign in licensed premises for exactly this reason. As a server, you are not a counselor and you are not asked to lecture customers, but you may decline to serve a visibly pregnant patron or a customer you suspect is pregnant — that decision is within your discretion and within your refusal authority. Customers who ask about treatment can be pointed to SAMHSA's national helpline (1-800-662-4357), Alcoholics Anonymous, or the California ABC's responsible-service resources. The point of the long view: the customer in front of you is part of a longer story, and your hour of refusal may matter more than the lost sale.
Last updated: May 2026