Alcohol, Drugs and Driver Responsibility
The numbers
Maryland's per se limit is 0.08 BAC for drivers 21 and older. Commercial drivers are held to 0.04, and drivers under 21 face zero tolerance at 0.02. You can still be convicted with a lower BAC if your driving is impaired - the number is evidence, not a safe-driving threshold.
Implied consent and consequences
By driving in Maryland you consent to a chemical test after a lawful arrest. Refusing brings its own license suspension, separate from the criminal case, and the refusal can be used against you. A DUI conviction carries fines, possible jail, license suspension, and mandatory ignition interlock, and penalties escalate with each offense. An open container of alcohol in the passenger area of a vehicle is illegal.
What impairment does
Alcohol slows reaction time, narrows attention, and blurs judgment first, which is exactly why impaired drivers feel fine. Cannabis, prescription medicines, and even some over-the-counter drugs can cause the same impairment and the same charges. Maryland prohibits driving under the influence of cannabis, and holding a medical cannabis card is not a defense.
Traps
The test punishes myths. Coffee, cold showers, food, and exercise do not sober anyone up - only time does, roughly one standard drink per hour for an average adult, and that average is not a rule to drive by. Another trap is treating 0.08 as the point where impairment begins; it begins well before that.
Rule of thumb: pick your ride before your first drink. If you are too impaired to drive, you are too impaired to decide how to get home.