Most Helpful Guy
I'm not sure that you can typically plea deal to insanity.
What would happen is the prosecution would still lay the charge, the defense would plead not criminally responsible, which means they accept the offense occurred but that the defendant didn't have mens rea (guilty mind, i. e. they weren't mentally aware that what they were doing was wrong). The prosecution could fight that by having their own witnesses testify that the defendant was mentally aware.
I imagine it might be possible in a case where there is some uncertainty about proving the facts that the prosecution could indicate behind closed doors to the defense that if the defense intends to plead 'not criminally responible' they won't fight that.
"severe emotional stress due to trauma" doesn't sound like it would cut it though. You need to be not just making bad decisions, you need to literally be not understanding the decisions you make are wrong.
A relatively recent case in Canada where they plea of not criminally responsible wasn't fought by the prosecution (that i'm aware of) was :
In that case, the killer's behavior around the time of the crime, the nature of the crime... was pretty consistent with someone who had lost touch with reality. I mean if he was sane, -why- did he do it. You'd have to argue it was a fetish or something and thought horrific he knew what he was doing and was doing it to please himself. But that sort of claim would be more likely if he'd taken reasonable steps to -get away with it-.
Most Helpful Girl
That most likely wouldn't happen. Not only is 16 old enough to be charged as an adult but they wouldn't give her a "deal" to plead temporary insanity. Her lawyer (who's probably court appointed) would have to find a medical professional to say she was ill and then prove it to the court.
And that just doesn't happen very often.
My advice would be to try and find similar cases and see what happens.