Sheriff Margaret Gimblett cleared Hui Yu, 23, a student from Beijing, of a motoring offence after dismissing evidence from two police officers identifying him.

She told Greenock Sheriff Court: “Without wanting to be derogatory in any way, sometimes it is said that all black people look the same at first glance, and the same can be said that all Chinese people can look the same to a native Scot.

“It’s only when you have time to look that you begin to see the differences.”

Mr Hui, a part-time supermarket worker who lives in Paisley, Renfrewshire, had been identified by the officers as the man they had stopped last December on a petrol station forecourt in Port Glasgow. They said that he had been driving a Rover 400, and had failed to produce his driving documents when he was asked for them. Mr Hui was subsequently charged with driving without insurance.

One of the officers, PC Michelle Meechan, told the court: “It’s my job to learn faces and I’m quite good at it.” However, Mr Hui denied the offence, claiming that he had been with his girlfriend, Meng Dong, 22, at her flat in Paisley when the offence was alleged to have taken place.

On finding Mr Hui not guilty, Sheriff Gimblett said: “This trial raises interesting issues because, when foreigners are in a country, they look different from the native inhabitants of that country and there can be a difficulty — even with experienced observers.”

She told Mr Hui: “In this case, I have no doubts that the police officers gave evidence that they thought was correct. However, I have great doubt about the reliability of that evidence and I have to give you the benefit of the doubt.”

A spokesman for the Commission for Racial Equality said yesterday: “The sheriff may have had her reasons for what she said, but these were not particularly helpful comments to make.”

Kenny MacAskill, the Scottish National Party’s justice spokesman, said that the sheriff’s remarks had been crass, insensitive and incorrect.

However, Mr Hui appeared to agree with Sheriff Gimblett. “It is true that people from one nationality or race can look the same to people from another nationality or race. It is the same for Chinese people — we find it quite hard at first to tell the difference between groups of Scots,” he said.

Sheriff Gimblett is no stranger to controversy. In 1999 she cleared three protesters who caused £80,000 damage to equipment during a demonstration at Faslane, the Royal Navy’s nuclear submarine base, claiming that their action was justified by a ruling under international law that nuclear weapons were illegal. She said afterwards: “I’m rather worried about my job after this. I certainly won’t be expecting a mention in the honours list.” The Government challenged the ruling, and in 2001 the Court of Criminal Appeal said that Sheriff Gimblett had been wrong.

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