A new law has made the legal drink-drive limit in Scotland lower than anywhere else in Britain.
The change reduces the legal alcohol limit from 80mg to 50mg in every 100ml of blood, BBC reported.
Campaigners believe the new limit will cut the number of deaths and serious injuries on Scottish roads.
The limit elsewhere in the country will remain at 80mg - the joint highest in Europe.
Experts have said the new 50mg limit means that an average man would be limited to just under a pint of beer or a large glass of wine, and women to half a pint of beer or a small glass of wine.
Northern Ireland is currently considering making the same reduction as Scotland.
Police and road safety campaigners have said an average of 20 people die on Scotland's roads annually as a result of collisions involving people who were driving while over the legal alcohol limit.
The number of people killed in drink-driving related collisions across Britain has fallen dramatically over the past 35 years, with the most recent figures showing that an estimated 230 people were killed in 2012, compared with 1,640 in 1979.
The 230 drink-drive fatalities in 2012 accounted for 13 percent of the all reported road deaths.
Of these, an estimated 165 were motorists who were over the legal limit, with the remaining 65 being other road users who were involved in the accident but were not necessarily over the legal alcohol limit themselves.
