How to demonstrate that lawyers should not defend the death penalty prisoners?

The defense lawyer shall, according to the evidence of the case and other materials, put forward the opinion that the criminal suspect or defendant is innocent or the lightest, mitigated or exempted from criminal punishment, and safeguard the legitimate rights and interests of the parties.

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.