legal ground
Article 38 of the Criminal Procedure Law: Defence lawyers may provide legal aid to criminal suspects during investigation; Acting as an agent for complaints and accusations; Apply for changing compulsory measures; Ask the investigation organ about the crimes and cases suspected by the criminal suspect, and put forward opinions. Article 39 of the Criminal Procedure Law: A defense lawyer may meet and correspond with a criminal suspect or defendant in custody. Other defenders, with the permission of the people's courts and people's procuratorates, may also meet and correspond with criminal suspects and defendants in custody. Article 40 of the Criminal Procedure Law: Defence lawyers may consult, extract and copy the case file from the date when the people's procuratorate examines and prosecutes the case. Other defenders may also consult, extract and copy the above materials with the permission of the people's court or the people's procuratorate.