A group of English traders, known as the Metric Martyrs, have had their appeals to the European Court rejected.
The Metric Martyrs say they have not failed
The campaigners from Cornwall, Sunderland, London and Surrey, were convicted for selling produce in imperial measures without displaying metric equivalents.
Their appeals against conviction were rejected all the way up to the House of Lords.
They then appealed to the European Court of Human Rights in Strasbourg, saying the law on price marking was an infringement of their right to free speech.
However, the Court has agreed with the convictions, and ruled that their argument was inadmissible.
Neil Herron, a director of the Metric Martyrs' campaign, said they had not failed, as the men had received huge backing from the public for their fight for British sovereignty over European regulations.
Other traders would now have more confidence to stand up against bureaucracy, he said.
"The courage shown by the Metric Martyrs in drawing their line in the sand, endorsed and passionately supported by the British public, is the beginning of the taking back of our right to self-determination."
The Cornwall pair - greengrocer Julian Harman and fishmonger John Dove, both from Camelford - were given conditional discharges in 2001 for selling sprouts at 39p a pound and mackerel at £1.53 a pound without displaying metric equivalents.