Alcohol, drugs, medication and fatigue
The impairment domain tests legal limits, the special limits for new drivers, the rules on medicines and drugs, and the signs of fatigue. The exam wants practical decisions, not moral commentary.
Alcohol
The general blood alcohol limit in Denmark is 0.5 per mille (0.05%). For drivers in their first three years after passing the B test, the limit is 0.2 per mille. Professional drivers are also subject to the lower limit. Alcohol is eliminated by time, not by coffee, food or fresh air. Even below the limit, alcohol slows reactions and increases risk. If you are stopped, police can require a breath or blood test.
Drugs and medication
There is zero tolerance for illegal drugs while driving. Prescription or over-the-counter medicines are not automatically safe: read the leaflet and ask the doctor or pharmacy whether the medicine affects driving. Do not drive if you feel drowsy, dizzy or unable to concentrate. Combining medicines, or medicine with alcohol, can increase impairment even if each alone seems mild. If a medicine carries a warning, follow it.
Fatigue
Tiredness is a major crash cause. Take a break at least every two hours on long journeys, and stop earlier if you yawn repeatedly, lose concentration or have heavy eyelids. A microsleep can last several seconds at speed. Opening a window or turning up music is not a reliable cure; a short rest or sleep is. Plan journeys so you do not drive when you would normally be asleep.
Worked example
A driver who passed the B test 18 months ago has one beer and estimates a blood alcohol level of 0.3 per mille. The general limit is 0.5, but the novice limit is 0.2. The driver is therefore over the legal limit and must not drive, even though the amount is below the general limit. Waiting an hour in the car with coffee does not make driving lawful; only time reduces alcohol.
Traps
Assuming 'one drink' is always safe; thinking coffee sobers you up; believing a prescription medicine is automatically legal to drive on; and ignoring the lower limit for new drivers.