Not sure how it works in Allegheny but in Westmoreland, a pool gets called to a certain court room, you fill out a few forms, get read an ass load of rules and then get questioned by a DA, the defense council, defendant, arresting officer (usually), and judge. If you get selected you sit in the court room until they get 12 jurors and 2 alternates. If not, you go back down to the jury commisioners room (where you sit ALL day) and could possibly be called to a different court room for a different trial.