(1) The judges read the briefs and the trial transcripts (or (1.a)have their clerks read them, really), (2)figure out what they think the answer should be, then (3)go into oral argument usually looking to solidify the position they've decided upon.
The Judges could patent this method of hearing arguments.
"The Avis WIZARD decides if you get to drive a car. Your head won't touch the pillow of a Sheraton unless their computer says it's okay." -- Arthur Miller