According to a comparative review by the Council of Bureaux (COB), blood alcohol concentration (BAC) limits vary considerably across the Green Card System. Depending on the country, the general legal limit ranges from 0.0 g/L to 0.8 g/L, meaning that the highest permitted threshold can be up to eight times higher than the strictest limit applied elsewhere in the region.
The review highlights four broad approaches to drink-driving regulation, including statutory zero-tolerance limits, lower thresholds of 0.1–0.4 g/L, the widely applied 0.5 g/L limit, and higher limits of up to 0.8 g/L in England, Wales and Northern Ireland.
COB also identifies stricter BAC limits for certain categories of drivers, particularly professional and novice drivers, with some countries applying zero-tolerance rules to specific groups.
The findings are particularly relevant given the extensive cross-border travel within the Green Card System. While BAC regulations are not fully harmonised, COB stresses that alcohol remains a significant road-safety risk regardless of the applicable legal threshold. Alcohol can impair reaction time, attention, visual perception and decision-making even at relatively low concentrations.
COB’s key message is clear: the safest approach is not to drive after consuming alcohol. Drivers travelling across borders should be aware of and comply with the national rules applicable in the country where they are driving.