Ending / twist doesn't make sense in retrospect
I enjoyed this film; the stellar cast are all pretty much at the top of their game.
But the twist really doesn't work when I think back about earlier events in the movie. It's true of many films with twists of course, but I think this one is actually pretty egregious.
1. How exactly does Aaron's courtroom appearance change anything? So he acted like a completely different personality, so what? By that point in the film the prosecution has already tried to imply that he just pretended to be two people to fool the neuropsychologist. And it's too late to change plea anyway.
But then doing the same trick in front of people (who presumably are less qualified to say whether it's an act)...changes something, apparently.
2. Why did Linney try to provoke him at the end anyway? The prosecution's case was basically won at that point.
By the film's logic, perhaps she was trying to provoke a violent outburst to show he was a brutal killer, but not *so* violent an outburst to make him seem like another person? Staying within this movie logic, it doesn't make sense for her to risk that.
3. So we discover that Norton is actually a cold, calculating killer, so why did he slowly kill the archbishop in his own house, trample blood all over the place, take the ring and then run away panicked? Throughout the film he would have had to be in control of his emotions many times and planned his moves very carefully, including how he managed to kill the girl (and note that was *before* he killed the archbishop).
Perhaps he really does have a split personality, but the other one is actually a hungry raccoon and only kicked in during the archbishop killing?
4. Also Norton's plan doesn't make a lot of sense. Why didn't he throw out the split personality earlier so they could plead insanity, since he was clearly such an expert of how the legal system works within that universe?
Furthermore, he couldn't have known that Gere would find the tape, that the neuropsychologist would be allowed to answer Gere's 3 questions, that Linney would try to provoke him at the end, or a whole slew of other events outside of his control.
Things could easily have gone another way, where he suddenly is faced with having to explain he has split personality and "transform" into Roy while being dragged away to death row.