Somebody asked an excellent question over on the IMDB forums about the climatic ending of this movie (spoiler alert obviously in effect):
At the end, when John and Lamar are confronting (each other) on the balcony, what was the motivation of John giving Lamar the choice to choose to kill him? To either prove it works and his work lives on with him prisoned or to prove it doesn’t work and still be imprisoned? After this scene it is revealed that precrime was shut down anyway. Why risk his life for something John knows doesn’t work 100% because if Lamar killed him, then precrime would still be in effect?
One answer given:
Dramatic effect? Seriously, I can’t think of any other reason. It’s one of a few things in the film that really bug me. It was as if he knew that Lamar would follow him out there. The whole scene makes it clear that both Anderton and Burgess both know there was a pre-vision of Burgess killing Anderton, yet they contradict that by pretty much admitting within the dialogue during the scene that they don’t know for sure.
Dramatic effect didn’t hurt, but I think there’s a better answer. Remember, the balls on Anderton’s murder had dropped – the precogs thought Lamar was going to kill John. But John told Lamar he had a choice:
“You see the dilemma, don’t you? If you don’t kill me, precogs were wrong and precrime is over. If you do kill me, you go away, but it proves the system works. The precogs were right. So, what are you going to do now? What’s it worth? Just one more murder? You’ll rot in hell with a halo, but people will still believe in precrime. All you have to do is kill me like they said you would. Except you know your own future, which means you can change it if you want to. You still have a choice Lamar. Like I did.”
The key phrase being, “Except you know your own future, which means you can change it if you want to.” What a change in character from earlier! Remember near the beginning of the film when John rolls the ball along the console and Danny Witwer catches it before it falls to the floor?
Anderton: “Why’d you catch that?”
Witwer: “Because it was going to fall.”
Anderton: “You’re certain?”
Anderton: “But it didn’t fall. You caught it. The fact that you prevented it from happening didn’t mean it wasn’t going to happen.”
This is Anderton’s analogy for Pre-Crime – he absolutely believes in it the way a religious person believes in their faith. He’s almost arrogant about it. But by the end of the film, he’s changed his mind. He’s seen the dark side of Pre-Crime and he comes to not believe in it any more. By now he’s realized his statement, “The fact that you prevented it from happening didn’t mean it wasn’t going to happen,” is false. A ball has no brain. Lamar does. John just presents him with the ultimate rebuttal to Pre-Crime, and then lets Lamar make his choice. A risk to be sure, but one he was willing to take, and ultimately he was vindicated. I think it’s fair to suppose that if Lamar had shot him and Pre-Crime worked, John didn’t want to live any more anyway. He had nothing to lose at that point, and nothing much to live for either. When Lamar didn’t shoot him, that was positive proof that Pre-Crime didn’t work, and John’s career was over anyway. John decided to put Pre-Crime to the ultimate test (since his own intended victim ended up getting shot anyway), and the ending neatly establishes that one way or the other, John is washing his hands of the whole mess.