A top government-appointed forensic scientist who openly criticised the legitimacy of the investigation into the death of British national Neil Heywood has resigned in protest over what she says have been a series of miscarriages of justice in China's legal system.

Wang Xuemei, the vice-president of the government-administered Chinese Forensic Medicine Association, said she could no longer be involved with an organisation that routinely serves up "ridiculous and false expert conclusions".

"I feel very disappointed with the status of China's legal medical expert team, and am increasingly desperate ... about the extremely ridiculous and false expert conclusion which turn up more and more," she said, in a searing indictment of China's judicial system. Her comments have sparked an outpouring of support from the country's increasingly outspoken legal community.

Beijing lawyer Wang Zhenyu told Fairfax Media that Ms Wang's role gave her an insider's view of the extent to which forensic opinion had been distorted in court, contrary to actual evidence.

"Because she is from inside the system, and has stronger feeling of its malpractice, it proves just how intolerable the system had become for her," he said.