I'm a writer, and in this chapter, the defendant is on trial for acts of terrorism. But he is pleading insanity, with no psychological evaluation because "his actions speak for themselves."
What would need to follow? I assume the Judge and defense attorney would be trying to prove whether or not he really is insane.
The story takes place in Paris, and I understand the Judicial System is different there. But I will take whatever answers I can get.
I dom't know about the French system. In the US the details of presenting an insanity defense are matters of state law, and vary significantly by state. In most states the defendant must notify the court in advance that such a defense will be raised, and must offer expert testimony that the defendant was not legally sane (as that state defines it) at the time of the crime. Without such notice and such testimony, the defense will not be considered.
For literary Precedent, perhaps the classic work is Anatomy of a Murder by Travers, an older novel still very readable. The author was a justice of the Supreme Court of the State of Michigan, and the law described was accurate for that state when the book was written.
