Although the examples provided describe situations where umpires are not necessary, there are still calls that are based on the umpire's discretion. Determining whether the infield fly rule should be in effect on a shallow fly ball, whether a player caught a ball and maintained possession, whether a pitch was foul-tipped in a two-strike count where the ball was not caught by the catcher, or whether a pitcher was guilty of a balk all require an impartial observer to interpret the rules and render a .judgement.