Rule 10 – Section 3 – FIELD UMPIRE
10-3-1 A field umpire shall aid the umpire-in-chief in administering the rules. He shall make all decisions on the bases except those reserved for the umpire-in-chief. He shall have concurrent jurisdiction with the umpire-in-chief in calling time, balks, infield fly, defacement or discoloration of ball by the pitcher, illegal pitches, when a fly ball is caught, or in ejecting any coach or player for flagrant, unsportsmanlike conduct or infraction as prescribed by the rules. In some instances, he will rule on the ball being fair or foul.
10-3-2 When there is only one field umpire, he shall make all calls pri marily at first, second and third unless the calls are more conveniently made by the umpire-in-chief.
10-3-3 If additional field umpires are used, they are referred to as base umpires and their normal positions are behind third and second bases. They have concurrent jurisdiction with the first field umpire.