legal ground
Article 35 of the Criminal Procedure Law
The responsibility of the defender is to put forward materials and opinions to prove the innocence, light crime or reduce or exempt the criminal responsibility of the criminal suspect and defendant according to facts and laws, and to safeguard the legitimate rights and interests of the criminal suspect and defendant.
Article 31 of the Lawyers Law
When a lawyer acts as a defender, he shall, according to facts and laws, put forward materials and opinions on acquitting the criminal suspect or defendant or lightening, reducing or exempting him from criminal responsibility, so as to safeguard the legitimate rights and interests of the criminal suspect or defendant.