Relevant laws and regulations:
Articles 35, 36 and 37 of the Criminal Procedure Law:
Article 35 A defender shall, according to facts and laws, put forward materials and opinions on the innocence, light crime or reduction or exemption of criminal responsibility of a criminal suspect or defendant, and safeguard the litigation rights and other legitimate rights and interests of the criminal suspect or defendant.
Article 36 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; Asking the investigation organ about the suspect's suspected case and giving opinions.
Article 37 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.