A lower drink-drive limit that could put motorists over the limit after just one drink came into effect in Scotland on Friday, prompting calls for tougher rules in the rest of Britain.
The changes sparked warnings that motorists crossing the border could be over the legal limit when they enter Scotland after consuming alcohol within legal limits in England.
The limit in Scotland was reduced from 80mg to 50mg of alcohol in every 100ml of blood, bringing it in line with other European countries including France, Germany and Spain.
Police advised drivers that consuming no alcohol is the best way to ensure they stay within the law, though the new limits equate roughly to just under one pint of beer for the average man or half a pint for a woman, subject to variants such as weight and metabolism.
In England and Wales the limit remains at 80mg of alcohol per 100ml of blood — one of the highest levels in Europe — but road safety campaigners called for stricter rules.
In a survey by motoring organisation RAC more than a third — 38 percent — of British motorists living outside Scotland said they believe the alcohol limit for driving should be lowered to the same level throughout the rest of Britain.
Road safety organisation Brake called for a limit of just 20mg.