GOVERNMENT experts will no longer be able to give evidence for the prosecution in court cases brought by their departments after a judge's ruling yesterday. 'It is not right to have a man perhaps not seen to be impartial to the prosecution case called as an expert for the prosecution,' Mr Justice Duffy said. He quashed a conviction against a construction company for failing to observe safety regulations prior to an accident in which two scaffold workers died. He said the guilty verdict was rendered unsafe because a senior Labour Department officer had given evidence for the Crown. 'I do not think it right that a member of the Labour Department should have given expert evidence in a case brought by that department,' the judge said. Patrick Cheung Wai-sun, for the Crown, warned the High Court judge that the ruling could lead to police triad experts also being barred from giving evidence. But Mr Justice Duffy said this was not his concern because he had to deal only with the case before him. Kai Tai Construction and Engineering was fined $40,000 on November 16 at Eastern Court. Magistrate William Ng convicted the company of failing to ensure that two scaffold workers wore safety belts when working on the 22nd floor of a building in Ap Lei Chau. During the hearing, Ben Beaumont, for the company, objected to the prosecution calling a Labour Department factory inspector as an expert witness. He was overruled by the magistrate, who relied on the inspector's evidence when giving reasons for his verdict, the court heard. The inspector, Chan Ho-wah, had told the magistrate the company's foreman should not have left the site without ensuring that the workers were using the safety belts. Mr Justice Duffy allowed the appeal on the grounds that the expert witness should not have given evidence. Leung Hoi-sung, 50, and Leung Kit-chuen, 39, plunged to their deaths when the scaffolding collapsed on December 13, 1993. Mr Beaumont said the company foreman took the safety equipment along to the site. But the experienced workers said they had their own belts and harnesses. After the foreman left, the scaffold workers scaled the building but chose not to use the belts. 'The trouble in Hong Kong is that the more experienced they are the less aware they are of safety measures,' said the judge.