Scottish Government plans to raise the age limit for buying alcohol in shops from 18 to 21 have suffered a major setback after being defeated.
MSPs backed a Conservative parliamentary motion, by 72 votes to 47, rejecting the proposals.
Students who claimed the plans would demonise young people earlier staged a rally outside the Scottish Parliament.
As MSPs debated the plans inside, Justice Secretary Kenny MacAskill branded his rivals "irresponsible".
Ministers have yet to bring forward legislation to raise the age - which they said was needed to help tackle Scotland's alcohol-fuelled violence and health problems.
We cannot go on as we are
Kenny MacAskill Scottish justice secretary
Leading the debate, Scottish Tory deputy leader Murdo Fraser told parliament: "The SNP are creating a ludicrous situation whereby students cannot buy a bottle of wine or a few cans of beer to enjoy in the hall of residence or flat.
"They are creating an even more ludicrous situation whereby a soldier returning from a tour of duty in Iraq or Afghanistan at the age of 20 cannot buy a bottle of champagne from the off-licence to celebrate with his wife on his return."
Mr Fraser said targeting 18 to 21-year-olds was discriminatory and pointed out that drink problems affected people of all ages.
Labour justice spokesman Richard Baker said it was more important to enforce proof of age cards, test purchasing and tougher sanctions for license breaches should be enforced.
"It is not just that the proposal is therefore in itself deeply flawed, it's that it's part of an artifice to allow political posturing from this government on tackling under age drinking to hide the fact they are failing to invest in measures which will actually make a difference," he said.
The Liberal Democrat Ross Finnie warned against stigmatising a generation with the plan, adding: "We believe it fails fundamentally to contribute to bringing about the essential cultural change in attitudes towards sensible drinking."
But Mr MacAskill said Scotland's drink problem was running up an annual tab of £2.25bn, adding; "We do need legislative change, because the status quo is unacceptable. We cannot go on as we are."
He criticised opposition parties for failing to put forward their own proposals and said trial bans of the 21 scheme in places including Stenhousemuir and Cupar had been "positive."
"The difference between us and the other parties is we recognise the scale of the problem and are willing to try to new approaches to tackle it," said Mr MacAskill.
"We won't sit back and watch the problems that have arisen."
Student group NUS Scotland has joined forces with the Coalition Against Raising the Drinking Age in Scotland (Cardas), to rally against raising the age outside parliament.
NUS Scotland president Gurjit Singh, said: "We hope this debate will force the government to rethink its unworkable and ill-thought out proposal."
And Green MSP Patrick Harvie hit out at the "Puritanism" surrounding the discussion of alcohol at Holyrood.
Recalling one debate, he said: "Speech after speech talking about the need to save communities from the demon drink by MSPs who then sauntered downstairs where huge trays of free booze awaited us all."
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