The infield fly rule is a specific regulation in baseball enacted to prevent a defensive team from intentionally allowing an easily catchable pop-up to drop untouched to force out runners on other bases. It applies when there are runners on first and second, or first, second, and third, with less than two outs. If the umpire judges that an infield fly can be caught by an infielder with ordinary effort, the batter is automatically declared out, and the runners may advance at their own risk. For example, if the bases are loaded with one out and the batter hits a pop-up that an infielder can catch, the batter is out, but the runners can attempt to advance to the next base.
This rule prevents strategic manipulation by the defense. Without it, infielders could intentionally drop the ball, creating a force play at multiple bases. This could result in a double or even a triple play. The regulation aims to maintain the game’s integrity and fairness, preventing a cheap out resulting from a deliberate play that exploits a technicality rather than demonstrating genuine defensive skill. Its adoption into baseball’s official rules significantly altered strategic considerations in specific game situations, ensuring that the outcome of such plays is determined by effort and ability, not by intentional error.