Understanding Alcohol Consumption and Legal Limits for Drivers
Last reviewed: 2026 · Driviology Road Safety Education Team
Quick Answer
Alcohol affects judgment and coordination well before a driver feels drunk, which is why Ontario sets strict legal blood alcohol limits, with even stricter zero-tolerance rules for novice and young drivers.
Understanding how alcohol actually affects the body helps explain why Ontario’s drinking-and-driving laws are strict, and why "I only had a couple" is not a reliable safety check.
How the Body Processes Alcohol
The body can only process alcohol at a fixed rate over time; nothing you do — coffee, food, a cold shower — speeds this up. Blood alcohol concentration continues to rise for a period after you stop drinking, which is why people are often still impaired well after their last drink.
Ontario's Legal Limits
Fully licensed drivers face criminal penalties above Ontario’s legal blood alcohol limit, and administrative penalties at a lower "warn range" limit. Drivers in the G1 or G2 stage, and drivers under 21, are held to a zero blood alcohol limit under Ontario law.
Why 'Feeling Fine' Is Not Reliable
Alcohol impairs judgment, which includes a person’s ability to judge their own impairment accurately. See our guide to alcohol’s effects on driving for how this plays out in reaction time, vision, and decision-making specifically.