The change, cutting the limit to 0.05 grammes of alcohol per decilitre (one-tenth of a litre) of blood, sparked warnings that motorists who legally consumed drinks in England -- where the legal limit is 0.08 -- before driving could be breaking the law if they crossed over into Scotland.
Scotland's reduced limit of 0.05 is in line with that in several European countries including France, Germany and Spain. It has prompted calls for the rest of Britain to follow suit.
The new limit equates to consuming roughly just under one pint (0.57 litres) of beer for an average man, or half a pint for a woman.
But Higgins said it was preferable to drink no alcohol if getting behind the wheel of a car. "Even at the new limit, you are three times more likely to die in a crash than if you had taken no alcohol," he said.
British road safety organisation Brake called for a limit of just 0.02.
"We have the highest drink-drive limit in Europe, sending out the dreadful message that a drink or two before driving is acceptable," said Brake's deputy chief executive Julie Townsend.