Would it be worth it to have a paragraph explaining what “diminished capacity” means, what happens when someone is deemed as such, and why Chris won’t be?
OK. Although Chris could very much be found to have diminished capacity. If found guilty at trial, there would almost certainly be a diminished capacity argument during sentencing.
It's important to understand that even though the chances of a trial are very low, what *could* happen in a trial is directly relevant in the plea negotiations.
EDIT: Diminished capacity has remained relevant for sentencing pretty much everywhere, even in places where it was removed from determining guilt. Backlash to diminished capacity was mostly over cases like the trial of Dan White (who killed Harvey Milk and George Moscone), who was able to avoid a murder conviction due to diminished capacity.
It's meanwhile stayed pretty normal for someone to receive a shorter *sentence* for diminished capacity, though this was weakened for many specific, serious crimes with mandatory minimum sentencing laws.
In Chris' case, he's lucky because recent legislation has effectively brought back diminished capacity to the actual trial.
EDIT 2: I should also clarify that while Chris' mental conditions can now be presented as a defense in trial, they might not help much, as such an argument would mostly be related to intent, rather than action. For incest, the reasons *why* it happened aren't as important as the fact that it happened.
Like, if you really wanted to stretch it, you could argue that Chris mental deficiencies meant he really thought he was "healing" Barb. The question is whether the court would even care, since he still did it. The argument would be like that after a car accident it's okay to reach inside an unconscious woman's vagina without permission if there's a dangerous object stuck inside it.
Chris is now allowed to make such an argument, but it might not do much good.