The blood alcohol level A of a person is the quantity of pur alcohol, in grammes,
contained in one litre of blood.
The unit is g.L-1. Without any other alcohol absorption, it usually decreases by 0.15 g.L-1 per hour.
In France :
if 0.5 < A < 0.8 the driver is in breach of the law and if A > 0.8 he commits an offence.