He is just an ordinary greengrocer who just wants to go about his business of serving customers in the way they want to be served

Barrister Michael Shrimpton

The case could be an important landmark, because Mr Thoburn is the first person to be prosecuted since the introduction of strict European regulations on metric measurements.

Defending the father-of-two from Sunderland, constitutional barrister Michael Shrimpton told the hearing that UK traders have a legal right to use Imperial measures under the provisions of the 1985 Weights and Measures Act.

"We say the European is entitled to his policies but he is not entitled to say that we in this country apply that principle in defiance of an Act of Parliament," he said.

He said the 1994 amendment to the act was not valid.

"Where there is a clash between an Act of Parliament and a regulation of the EC it is the Act of Parliament which takes precedence," he said.

'Honest trader'

He described Mr Thoburn as an honest trader just wanting to go about his business.

"There is no evidence of deceit or dishonesty in the conduct of this man," he said.

"He is a man of some courage who has stood his ground in the face of criminal prosecution.

"He is just an ordinary greengrocer who just wants to go about his business of serving customers in the way they want to be served."

Barrister Eleanor Sharpston, QC, representing the city council, told the court that the prosecution was brought to "enforce a valid act of Parliament".

'Metric martyrs'

Trading standards officers had a duty to protect consumers from confusion, which could arise if there was no consistency among traders, she said.

The case is the country's first prosecution of a market trader for refusing to sell fruit and vegetables in metric measurements.

It was due to take place at Sunderland magistrates court but was moved by District Judge John Morgan to the council chamber at Sunderland City Council after a power cut.

The legal battle started last summer when local authority trading standards officers seized Mr Thoburn's scales.

Mr Thoburn, 36, and his fellow trader Neil Herron, a fishmonger who has also been ordered to change his scales, became "metric martyrs" to some and a legal expenses fund was set up.

The case has been taken up by the UK Independence Party (UKIP) which believes it could decide the future of the nation's weights and measures system.

Steven Thoburn said he welcomed his day in court

Party leader Jeffrey Titford MEP, who is backing Mr Thoburn, said outside the court on Tuesday that the hearing served to "highlight the way the EU is imposing its will on British culture".

But Vivian Linacre, director of the British Weights and Measures Association, said before the hearing started: "Ultimately we are confident this will go our way, but it could go all the way to the House of Lords."

Mr Thoburn, who is now using dual measure scales, gathered support from shoppers to hand over a 5,000-signature petition on the issue to Downing Street.

The campaign is backed by a number of celebrities from the entertainment world and 500 people attended a fundraising dinner at Sunderland Football Club's Stadium of Light at the weekend.

Europe's 1994 Units of Measurements Regulations came into effect on 1 January last year.

Mr Thoburn failed to comply with a notice issued by its officers to convert to metric measures at his stall.

The hearing was adjourned until Tuesday and is scheduled to last until Wednesday.