Lower limits for drunk drivers to lose licence on the spot

More people caught driving while under the influence of alcohol could lose their licence on the spot after a new law comes into force on 1 June.

The law lowers the limits for immediate withdrawal of a licence from a blood alcohol level (BAC) of 1.5 grams per litre to 1.2 grams.

Other sanctions for drink-driving will still apply from a BAC of 0.5 grams per litre upwards.

While blood alcohol level (which is legally fixed in grams per litre of blood) can only be accurately determined by taking a blood sample, police can estimate BAC by taking into account factors such as a person's weight, gender, number of drinks consumed and alcohol content.

The most accurate formula is: (V * t * 0.8) / (0.7 or 0.6 * m), where V is the volume of drink (measured in millilitres), t is the degree of alcohol in percentage and 0.8 is the density of the alcohol. In the second half of the equation, 0.7 is the diffusion coefficient for a man whereas 0.6 is used for a woman, and m is the person’s weight in kilograms.

For the same weight and quantity of alcohol consumed, the concentration of alcohol in the blood is generally higher in women than in men.

A person’s BAC is highest after 30 minutes if they have not eaten and 60 minutes if they have. It then begins to drop. But a breath test can also be influenced by very recent consumption.

It is advised that no one who intends to drive should have any alcoholic beverages at all.

The stricter measures for driving while under the influence of alcohol mean that a person could lose their licence for getting behind the wheel after around four glasses of an alcoholic drink (with some variation depending on the individual and the type of drink).

The measure was introduced by Belgium’s mobility minister Georges Gilkinet (Ecolo) as part of a greater reform of the country’s highway code.

In 2021, one in 10 drivers involved in a road accident with injuries was found to have been under the influence of alcohol.