THE headmaster of a blind woman whose father was acquitted of having sex with her said the case could make blind people vulnerable to attacks. 'If their evidence can be judged as inferior to others, is it not logical to think they are more likely to be picked as targets for attacks?' said Dr Simon Leung Man-on, who is director of a school for the blind. His comment comes amid concerns raised by the Hong Kong Council of Social Service that the ruling could throw doubts on blind people's competence to testify in court. The 44-year-old father was cleared of incest with the 18-year-old after a judge said the woman's disability prevented her from making a reliable identification. The woman had said she knew it was her father who had sex with her because she recognised his voice. She also heard keys jangling and could smell tobacco. Her father, who cannot be identified to protect the woman's identity, had a habit of wearing keys on his belt and is a smoker. The council has written to Attorney-General Jeremy Mathews to clarify the admissibility of evidence given by people with visual impairment. Speaking for the first time since the controversial trial, Dr Leung said: 'I am very disappointed. The judge knows very little about what blind people are capable or not capable of doing. 'We fear a precedent could be set. How will this case affect other blind people who may be robbed or indecently assaulted? 'What should they base their evidence on? What legal protection do they have? 'If the credibility of their evidence can be questioned simply because they cannot see, this is a case of discrimination. 'When sighted people can base their evidence on what they saw, why can't blind people base their evidence on their other senses such as hearing? 'If the court is saying the evidence given by them is inferior to others, it is unfair,' he said. In the council's letter, director and legislator Hui Yin-fat asked whether there were guidelines on the issue of voice identification. Mr Hui said visually impaired persons relied heavily on sound to make sense of the happenings around them. He said blind people usually developed better hearing ability especially in recognising people by their voices. But Judge McMahon said no evidence had been given to show whether a blind person developed greater hearing ability and was therefore better able to recognise voices. Dr Leung, who has 14 years of experience in teaching blind students, said: 'I am very shocked by the suggestion that a blind person cannot recognise even the voice of his father. 'I believe a sighted person can recognise his father's voice even with his eyes shut. 'I do not believe a blind person needs to develop exceptional hearing ability to do that. 'And I do know blind people who are able to tell who I am only by talking to me on the phone, even though we have not been in contact for some four years.' Dr Leung said Judge McMahon was in danger of stereotyping when he suggested it was 'tragic' to be blind. 'I know a lot of blind people who are enjoying a happy life,' he said.