And as for the insanity defense... don't get me started on grandstanding lawyers trying to get people out of serving time for the crime they committed.... 1 the lawyers job is to protect his rights, 2 not to get him found innocent for something he clearly did. 3 But they make it such a competition that right & wrong get lost in the contest of who wins.
1. The defense lawyers' job is to defend the accused, not just to protect his rights.
2. The defense lawyers don't 'get someone found innocent'. The lawyers on both sides make their best cases, then the jury decides the verdict.
3. That's how the adversarial system works. As you say, the objective truth is irrelevant; the accused may in fact be a murderer, but if the prosecution can't prove it beyond reasonable doubt, he should walk free. And rightly so.
This disagreeable fact is based on Blackstone's FormulationWiki
of the eighteenth century: better that ten guilty persons escape than that one innocent suffer.
He should get the medical care he needs but he also needs to be held accountable for his actions.
Yet the law often recognizes that responsibility can be diminished in some circumstances, such as mental illness. So this might be a valid defense.