Article 37 of the Criminal Procedure Law is the responsibility of a defender to provide materials and opinions on whether a criminal suspect or defendant is innocent or light, or to reduce or exempt his criminal responsibility according to facts and laws, and to safeguard the litigation rights and other legitimate rights and interests of the criminal suspect or defendant. 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.