The darkness in the middle created by Fletcher creates a literal seperation of sides; a wall. The darkness is contrasted with the light that is casted on Anderton and Witwer's faces. They stand equidistant from Fletcher and have the same light on their faces and bodies. They even stand eye-to-eye, even though the height of the actors varies by three inches (Farrell being the taller of the two).
A close shot created the perfect effect, making visible the distance between the two highly ranked officers of the law, as well as keeping the facial features still visible.
The two sides of the screen are very equal in appearance, the only varying factors are the clothes, and what is immediately behind the head of Anderton and Witwer. Anderton is in a polo, which tends to be more relatable attire than the suit that Witwer wears. Suits are more often thought to be worn by "men who mean business" and have a colder appeal. What is directly behind the heads of Anderton and Witwer was probably not intentional, however it still adds to the shot. Behind the men is the screen that Anderton uses to conduct the break down of each crime scene. The lighting used in the room creates a warped effect on the screen. Inbetween the two men there really isn't any effect, but behind Anderton's head it gets very messy and warped, which is how his mind works as well. He believes in pre-crime and follows the rules (for the beginning of the film), yet he still has a void that needs to be filled, which he fills with illegal drugs. Not so morally sound for a chief. As for what is behind Witwer's head, it goes along with how his mind works as well. There are a few lines right near the top of his head. Very exact, very precise, just like his motives. His goal is to find the hitch in pre-crime, to find a fault.
