Shanghai authorities are threatening to revoke the licence of a lawyer who has defended a number of activists in high-profile cases after he posted essays critical of the mainland's legal system on overseas websites. The Shanghai Bureau of Justice will hold a disciplinary hearing on Friday to determine how to punish Guo Guoting after accusing him of 'defiling and slandering' the Communist Party and state government, according to Mr Guo and documents about the case. Mr Guo said the possible penalties ranged from a ban from practising law for one year to disbarment. The Shanghai Bureau of Justice could not be reached for comment. The lawyer is best known for defending another activist lawyer, Zheng Enchong , who advised residents involved in hundreds of property disputes with the city before he was jailed in 2003. Mr Guo said his defence of Zheng, a recent article alleging abuse in prison of a member of the banned Falun Gong spiritual movement and his efforts to appeal against the 12-year jail sentence handed to dissident Huang Jinqiu , had angered authorities. Zheng is now serving three years in jail for revealing state secrets after he contacted an overseas rights group about labour and property disputes in Shanghai. At the time of his arrest, he was advising residents suing a city district, alleging that government officials had colluded with property tycoon Chau Ching-ngai to transfer land. Chau was sentenced to three years in jail for financial crimes, but the land deals were never raised in court. There have been persistent rumours that the property developer has already been released on parole, but the city government has denied this. Huang, a former journalist, was sentenced by a court in Jiangsu province in September for posting articles on the internet.