The Campaign for Real Ale (CAMRA) has condemned the government's decision to introduce a minimum 95 per cent liquid pint as "farcical".
The group, which had lobbied unsuccessfully for a compulsory 100 per cent liquid pint, made a submission to ministers this week attacking the decision.
It claims the 95 per cent minimum rule, with top-ups on request, agreed by the Department of Trade and Industry in March will lead to more short measures being served in the UK's pubs.
It also claims that licensees will be able to get away with serving only 92 per cent liquid since prosecution is unlikely unless the pints falls significantly below the 95 per cent limit.
Chris Howells of the Trading Standards Institute told real ale newspaper What's Brewing that licensees were unlikely to be prosecuted unless the levels fell seven to eight per cent below the 95 per cent limit.
He added that the institute would support a 100 per cent liquid pint law.
Mike Benner, CAMRA's head of campaigns, said: "It's ridiculous to suggest to consumers that a pint is only 95 per cent of a pint in the first place, but as that is not enforceable in the courts the proposals are clearly unworkable. The government should scrap these plans and introduce laws for a 100 per cent liquid average."
But the trade has slammed CAMRA's efforts in the past.
Trade leaders say there is little consumer concern over the current regime and hence no need for a change in the law.
They also say a 100 per cent liquid pint would deny many drinkers the head they love and cost licensees thousands in extra glassware and beer wasted through accidental overfilling.
The 95 per cent rule is due to be introduced this summer but ministers may still change their minds if they feel there is public demand for tougher legislation.
The story so far:
Mar 1995:consumer group CAMRA urges action over short measuresJan 2001:trade leaders warn that a full pint law could mean the end of traditional handpumpsFeb 2002:CAMRA's campaign reaches the House of Commons after it launches a series of posters encouraging pub-goers to get involvedMar 2002:ministers say they are minded to introduce a 95 per cent minimumJuly 2002:the trade awaits the Department of Trade and Industry's final decision after consultation ends.
Related articles:
Campaigners continue fight for 100 per cent liquid pint (14 June 2002)
Licensees' 'Duckometer' guide aims to reveal short pints (17 May 2002)
Trade wins fight against 100 per cent liquid pint (18 March 2002)