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How do base umpires help enforce baseball rules?

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In baseball, base umpires are officials stationed near first, second, and third base who work alongside the home-plate umpire to conduct the game and enforce its rules.12

Their primary responsibilities include:

  • Ruling on Base Plays: Base umpires are responsible for calling runners safe or out at their respective bases.2
  • Determining Fair or Foul Balls: Along with the home-plate umpire, base umpires may rule whether a hit ball is fair (within the foul lines) or foul (beyond the foul lines).12
  • Calling Illegal Motions: Any umpire, including those on the bases, has the authority to call an illegal pitching motion known as a balk.2
  • Assisting with Appeals: Base umpires may be consulted by fellow officials if an umpire was out of position to see a play clearly. Additionally, the first- or third-base umpire may be appealed to regarding whether a batter has taken a full swing for a strike or checked their swing.12