Based on the basic principle of taking the law as the criterion, under no circumstances may they help criminal suspects or defendants fabricate confessions, collude in confessions, forge, or destroy evidence. Or threaten or induce witnesses to provide false evidence.
2. Submit materials and opinions that prove that the criminal suspect or defendant is innocent, that the crime is minor, or that the criminal liability is reduced or exempted.
Legal basis: Article 35 of the "Criminal Procedure Law of the People's Republic of China": The defender shall submit materials and opinions proving the innocence of the criminal suspect or defendant, or reduce or exempt him from criminal liability based on the facts and law , the responsibility to safeguard the legitimate rights and interests of criminal suspects and defendants.