The Impairment Ladder

Rising blood alcohol produces a predictable progression. The boundaries are approximate, but the order is not:

Level	What happens	Why it matters for driving
Low	Some inhibitions lost, ability overestimated, reaction slowed	The deadliest band — it feels like nothing
Moderate	Vision, speech and coordination impaired	Impairment becomes visible to others, not always to you
Higher	Difficulty controlling the body, impaired balance, double vision	Driving is plainly impossible; judgement long gone
Very high	Deep sedation, then risk of coma or death	A medical emergency, not a driving question

The critical teaching point is the first rung. The level low enough to feel harmless is already slowing reaction and inflating confidence — and it comes with no internal alarm. The dangerous band for driving isn't stumbling-drunk, which at least announces itself; it's the "one or two, I'm fine" band, driving with degraded reactions and a raised opinion of your own driving.

Key takeaways

Impairment climbs in a fixed order — inhibition and reaction first, then vision, speech and coordination, then balance and control, then sedation
The lowest rung is the deadliest for driving: reactions already slowed, confidence already inflated, and nothing that feels wrong

Quick check

Which level of alcohol is most dangerous for driving, and why?

A) The highest — a driver who can barely stand is the greatest risk on the road.

B) The lowest — reaction is already slowed and confidence already inflated, but nothing feels wrong, so the driver drives.

C) The moderate band, where vision and speech are affected.

D) All levels are equally dangerous.