Alcohol, Drugs, and Impaired Driving
How alcohol works
Alcohol is a depressant that impairs judgment first, then reaction time, then coordination - which is why a driver can feel "fine" while already unsafe. North Carolina's legal limit is 0.08 BAC for drivers 21 and older, 0.04 for commercial drivers, and any measurable alcohol for drivers under 21 under the state's zero-tolerance law. A standard drink - 12 oz of beer, 5 oz of wine, or 1.5 oz of 80-proof liquor - contains about the same alcohol. BAC rises with body weight, number of drinks, time, and food; nothing speeds sobering except time. Coffee, cold showers, and exercise do not lower BAC.
Other drugs and the law
Impairment also comes from marijuana, prescription medicine, and even some over-the-counter cold remedies. North Carolina's DWI law covers any substance that makes you less able to drive safely. Refusing a chemical test triggers an immediate license revocation under implied consent. Open containers of alcohol in the passenger area are illegal. DWI penalties escalate with prior convictions and with a BAC of 0.15 or higher.
Traps
Test writers love "the legal limit means you are safe below it" - false; you can be convicted of DWI below 0.08 if your driving is impaired. Another trap: "one drink per hour keeps you under the limit" is not a legal rule. Also watch for the claim that refusing a test has no consequence.
Worked example
A 150-pound driver has three drinks in one hour and feels alert. Judgment and reaction are already impaired, and if BAC reaches 0.08 he is legally drunk regardless of how he feels.