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There is some wacky terminology in the major sports of North America, including the hat trick, the triple-double, scat back, and many more. Which reminds us to bring back our periodic series on explaining baseball terminology. This edition is dedicated to the infield fly rule in baseball.
Baseball’s infield fly rule calls for the hitter to be called automatically out on a pop-fly ball hit to an infielder, if there are runners on 1st and 2nd base, or bases loaded, with less than 2 outs.
When the situation arises, it is the umpire’s discretion to call the batter out, on the spot, whether or not the pop-up is caught.
Sounds strange, right? Why call a batter out while the ball is still in the air?
Well, in the late 19th century, Major League Baseball infielders got creative and invented a way to deliberately drop popped-up fly balls to then quickly put out the lead runner, or the fastest runner, or to nimbly turn double (or even triple) plays.
So while the rule might seem to be the gifting of an out to the defense, in reality the purpose of the infield fly rule is to protect runners on base, by not forcing them to advance. An infield fly rule call eliminates the potential for force outs on that play.
It’s not as complicated or confusing as it may seem. Let’s examine the problem, followed by the solution.
What Problem Does Baseball’s Infield Fly Rule Address?
The infield fly rule prevents the defense from benefitting if an infielder pretends to track a pop-up in preparation of making the catch, but at the last instant purposely lets the ball touch the ground. Infielders could let the ball pop out of their gloves, or just field it on a bounce.
The reason behind this is, while the ball is in the air, runners have to stay close to the base they initially occupied, to avoid having a fielder catch the ball and throw back to double them off that base.
The infield fly rule allows runners to stay on bases that under other circumstances they would be forced to leave, and therefore be prone to a force out.
The infield fly rule relates to force outs. Force outs are when an out is recorded without a player holding the ball and touching a runner with it. Example: If a runner is “forced” to leave a base because the hitter (and other runners) are behind him and coming, like being on 1st base and having to run to 2nd base because the hitter is running to 1st base.
That runner is “forced” to move off 1st base. So if there is a runner on 1st base, or runners on 1st and 2nd base, or even with the bases loaded, all non-hitter runners can be forced out by a defender holding the baseball touching the base before the advancing runner gets there. Because it’s a “force play,” the defender does not need to tag the runner, while off a base, with the ball.
Why Baseball’s Infield Fly Rule is Necessary

The force out was included in the original rules that resulted in the creation of baseball as we know it today. The Knickerbocker Rules (called the “New York style baseball” rules) were introduced by Alexander Cartwright in 1845, to formalize the game and differentiate it from other forms of baseball (like the “Massachusetts Game”).
Early baseball experts understood that having to tag a runner ~ or even get a runner out by throwing the ball and hitting a runner with it, which was allowed in early baseball! ~ created confusion when runners would stop between bases. Or, runners could purposely cause pickles, extra throws, and maybe even errors to advance bases safely.
The force out eliminated the requirement for tags for outs under certain circumstances. The force out rule eliminates tags for runners who are “forced off” their base, as in a runner on 1st having to go to 2nd base on a ground ball. A force out is available at the base ahead of him.
When was the Infield Fly Rule Put in Place?
The infield fly rule was introduced in 1895 by the National League, because keen infielders began to purposely drop popped-up fly balls to then get outs by forcing out runners on base. In these circumstances, runners were essentially pinned near their bases while the ball was in the air.
The rule originally applied only when there was 1 out. Today’s infield fly rule became effective in 1901.
Savvy Infielders Caused Invention of the Infield Fly Rule
It didn’t take long for infielders to figure out a way to use the force outs to their advantage. They learned on pop-ups to the infield, runners on base had to stick close to the base they occupied, so as not to get doubled off after a catch.
Keen infielders learned to pretend they had a bead on the balls, therefore keeping runners close to the bases they occupied. However, at the last second the fielder would let the ball bounce on the ground once, then hurriedly throw to the base ahead for the out. Often they were good enough to turn double plays doing it, if planned or practiced ahead of time.
Infield Fly Rule Resolves an Unfair Advantage
Infielders had a significant advantage over the runners in these situations, so the infield fly rule was introduced.
With it, if an infield fly rule situation is present, once a ball is popped up and an infielder can make a play on it, the batter is automatically out, even while the ball is in the air and in play. The umpire yells out “infield fly!” or “Infield fly, the batter is out,” and this erases any force outs on the play.
The runners get the option of staying on the base they had occupied, or trying to advance at their own peril.
What is an Infield Fly rule Situation?
- Must be less than 2 outs in the inning.
- Must be runners on 1st and 2nd bases, or bases loaded. (Infield fly calls cannot happen where there is at least 1 runner in force-out position).
- An infielder can catch the ball with “ordinary effort” in fair territory (on close calls umpires might call out “infield fly if fair!”)
- The pop-up fly ball can’t be a bunt, or a line drive
These are outlined in Official Baseball Rules under Rule 5.09 (Batter is out).
Baseball’s Infield Fly Rule is an Umpire’s Judgment Call

Infield fly rule calls are rarely black and white. Any umpire on the field can call the infield fly rule on a play. The rule is left entirely to the umpire’s discretion, so protests on such plays are futile. Each umpire can view “ordinary effort” differently.
It is important to note that in making the “ordinary effort” call, all circumstances must be included including wind, weather, sun, lighting, field moisture, positioning of the defense as a team, and skill level of the infielder involved.
Some shortstops are known to go back on popups very well and make catches on the outfield grass; others are not good at it at all. Umpires familiar with players can more easily ascertain if a popup could have been caught by an infielder without extraordinary effort.
Final Words on the Infield Fly Rule in Baseball
The infield fly rule was invented to remove the ability of infielders to intentionally fail in making an easy catch, therefore forcing runners to advance to the next base. If on a play the infield fly rule is called, runners can stay where they are without fear of being forced out. And the batter is automatically called out regardless of what happens with the pop-up.
The rule essentially is a base runner protective measure, to prevent them from being easily forced out or doubled up.
Related Questions
Question: How far away from home plate can the infield fly rule be called?
Answer: There is no distance requirement. An infielder can run out as far as he wants in the outfield, and as long as he clearly can catch the ball easily, the rule can be called. In fact, on a play where a popup landed between the shortstop and left-fielder in the 2012 National League Wild Card Game, the ball dropped 225 feet from home plate. The umpire still called the infield fly rule because until the very last second it appeared the shortstop would catch the ball.
Q.: Is it hard for umpires to judge whether or not a popped-up ball could be caught by an infielder with “ordinary effort.”
A.: Sometimes. Infielders do no have to be on or inside the infield dirt to trigger an infield fly. They just have to call the ball and be ready to catch it in fair territory. When an infielder runs into the outfield quite away still with his eye on the ball, the umpire has to decide the level of effort that would be required to make the catch. Complicating these situations are charging outfielders who also might call for the ball. These types of plays, in “no-man’s land” between infielders and outfielders, can cause confusion for all involved including umpires.
Q.: Is there an “outfield fly” rule?
A.: No. However, an outfielder might catch a ball after an umpire calls the infield fly rule, if the umpire judges that even though the baseball was handled by an outfielder, an infielder could easily have caught the ball. These calls are a matter of watching an infielder chase or set up under a ball, to see if indeed the infielder can make that catch expectedly.
See Also:
The 13 Oldest Baseball Stadiums in MLB Today
How Many Outs are in an Inning in Baseball?
USSSA vs USA Bats: Here are the Difference
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