“...and cannot help their own defense.”
This is even worse. I can just hear his lawyer. “Judge, my client tells everyone he meets how he sliced that white b*$%* up, and will continue to do so in front of you and the jury. That, by definition, will not be helpful to his defense, and therefore he cannot stand trial.”
so if you want to be an evil mastermind and be a serial killer, when you go to trial, do like Tom Hanks and pretend your nose is stopped up like in Forrest Gump and you can get off.