Legal basis: Criminal Procedure Law of People's Republic of China (PRC).
Article 38 A defense lawyer may provide legal aid to a criminal suspect 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 41 Defenders who believe that the evidence materials collected by public security organs and people's procuratorates to prove the innocence or minor crimes of criminal suspects and defendants have not been submitted have the right to apply to the people's procuratorates and people's courts for retrieval.