The grocer is trialling the system at 10 stores in Scotland and is expecting a wider roll-out across its estate. Now it is calling on other chains to follow suit, in a move that could radically alter the character of the trade's united approach to responsible retailing.
Asda already operates the nationally-recognised Challenge 21 policy, but decided to introduce the new scheme after 23 per cent of people it surveyed thought a group of 16-year-olds were aged over 21.
Retail director Andy Clarke said: "A mistake on guessing someone's age could mean a hefty fine and a criminal record.
"Challenge 21 helped make asking for ID in our stores less of a taboo, but our research now highlights the need to go one step further in a bid to help protect our colleagues."
Clarke said: "It's only when we act as a united industry that we can really make a difference to the impact of under-age drinking. We are confident that all of our customers who are lucky enough to look under 25 will understand the importance of this campaign, just as they did when we launched Challenge 21. What we want to see, though, is a culture in the UK where being asked for and showing ID isn't an issue. It's just responsible retailing."
In-store signs and leaflets advertising the Challenge 25 scheme have been installed in stores in Edinburgh Chesser, Falkirk, Grangemouth, Kirkcaldy, Alloa, Coatbridge, Cumbernauld, Dunfermline and Galashiels to inform customers about the change in policy.
But Sainsbury's, Waitrose and Tesco say they have no current plans to implement a similar scheme.
Wine & Spirit Trade Association chief executive and Retail of Alcohol Standards Group spokesman Jeremy Beadles said: "There are businesses, mainly in the on-trade, who have tried a Challenge 25 policy. They are particularly in areas where the companies involved have had high levels of problems with young people trying to gain entry and where there have been issues with enforcement officers."
Beadles said the policy was unlikely to become widespread in the off-trade, unless drinks shops faced particular local problems.
"The aim is to carry on with a national Challenge 21 policy, but some businesses will adopt a stricter policy in specific areas," he said.