An independent public-interest reference on impaired driving AboutSources & MethodContact
The Law · Ref L-01
0.08

How the Limit Became 0.08

The per se threshold wasn't discovered in a laboratory. It was negotiated — one decade, one statute, one study at a time.

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How the Limit Became 0.08
By the Numbers
2–3×the crash risk at 0.08 BAC relative to a sober driver.
Source: NHTSA relative-risk estimates
0.00

Zero-tolerance jurisdictions write the limit as none at all.

~1 hr

To clear roughly one standard drink. Coffee, air and time only supply the time.

18

Scored clues across the three standardised field-sobriety tests (HGN 6, walk-and-turn 8, one-leg-stand 4).

1st

A first offence already puts a licence at risk. See Consequences.

Filed in support

The Record

All 20 entries →
Alcohol Espresso cup and spoon on a saucer atop a woven placemat and wooden table

The Morning After

Sleep is not a breathalyser. Many drivers are still over the limit at nine a.m.

Ref A-01 · 7 min readRead →
The Law Per Se Laws, Explained

Per Se Laws, Explained

Above the line you are impaired by definition — no bad driving required.

Ref L-02 · 7 min readRead →
Underwriting the record
Consequences Digital speedometer and dashboard display seen through a car's steering wheel at dusk

The Ignition Interlock

A breath test wired to the starter motor — and whether it works.

Ref C-02 · 4 min readRead →
MeasuredSection 01 · 5 entries The LawSection 02 · 4 entries AlcoholSection 03 · 4 entries DrugsSection 04 · 3 entries ConsequencesSection 05 · 4 entries
Filed in support
Comparison · General BAC limits by jurisdiction g/dL, standard drivers · lower novice/commercial limits common
United StatesUtah 0.050.08
Canadacriminal; 0.05 provincial warn0.08
United KingdomScotland 0.050.08
France0.02 novice0.05
Germany0.00 novice/commercial0.05
Italy0.05
Spain0.03 novice0.05
Australia0.05
Japan0.03
Sweden0.02
Norway0.02
Poland0.02
Czech Republiczero tolerance0.00
Hungaryzero tolerance0.00
Underwriting the record
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General information on road-safety law and science — not legal advice.