First, it will not make any difference in CCP's unjust "legal system".

If there is any possibility to save Yang's life, it is the insanity defense. By finding that Yang was insane, even if it is for the moment, the court could not sentence him to death. That's the best possible outcome.

Let's face it: In any legal system, Yang was not supposed to take the justice into his own hand by killing police.

You want the trial to be a forum to condemn the police brutality. However, that may not be the best interest of Yang.