What Is Obstruction in Baseball?

Navigating Obstruction Calls in Baseball: The Rules, Types, and Penalties Explained
Written by Mark Bailey
Last updated on

Obstruction is a ruling that can only be made by an umpire in a baseball game. A runner cannot interfere with a fielder, and a fielder can also not interfere with a runner. 

This rule was put in place to mainly prevent any injuries. Collisions can happen in baseball, and when they do, they aren’t pretty. Obstruction is a rule created to encourage players to avoid collision-possible situations as much as possible. 

This blog will cover the basis of obstruction as well as how umpires are told to look at the rule.

  • The current standard size and weight of a baseball, as determined by MLB regulations, is between 9-9.25 inches in circumference and 5-5.25 ounces in weight.
  • Variations in the size of baseballs exist at different levels of play, with Little League baseballs being slightly smaller and softerball softballs being larger and heavier.
  • The anatomy of a modern baseball includes a cork core and two pieces of rubber covered with cowhide leather.
  • Various factors such as materials used, environmental conditions, and wear and tear can affect the size of a baseball during gameplay.
  • Baseball size has an important impact on players’ performance and safety, with changes in size affecting how pitches move through the air and how easily balls are caught or hit.

What is an obstruction in baseball?

Obstruction is normally when a fielder obstructs a baserunner from running legally down the base path. 

You might have heard of the term “interference” as well. While that is also a rule, interference typically occurs when a baserunner interferes with a fielder. Obstruction is the other way around. For example, a fielder who does not have the ball cannot block or attempt to hold up a runner up while he is running. The runner cannot be touched or interfered with. 

There are a variety of ways that obstruction can be called by an umpire. It could be something as simple as a fielder standing in the middle of the base path while a runner is coming by. If the runner has to avoid the fielder, obstruction will be called. The runner is allowed a straight line to each base. 

How is obstruction called by umpires?

Just like any call, the umpire will signal obstruction by pointing at the violator of the rules. An umpire considers a couple of factors into account when deciding whether to make an obstruction call or not. 

First, every base runner is allowed a straight line to each base and 3 feet on both the left and right of the line. This is called the base path

The runner cannot be interfered with or even touched while running on the base path. The umpire must make sure the runner was on the base path when the obstruction occurred. 

If contact is made while the runner is outside the base path, there is no obstruction; instead, the runner is called out. This is because a runner is ruled out as soon as he leaves the base path. 

If an obstruction is called, the runner is granted the next base. For example, if the runner runs from first to second and is obstructed, he will be granted third base. This is only true if he is more than halfway to the next bag. If he is not halfway, he will just be given second base.

Types of obstruction

There are two types of obstruction in the game of baseball. First, there is the fielder’s obstruction. This is the traditional kind of obstruction, as it is the most common. When a fielder makes contact with or interferes with a runner while he is in the base path, the fielder’s obstruction will be called. 

The second type of obstruction is the umpire’s obstruction. This is when an umpire either interferes with a baserunner or a fielder during a play. 

However, a ball that hits an umpire is not ruled obstruction. This only occurs when an umpire finds himself in the middle of the baseline and hits a runner. It also occurs when a fielder makes contact with him when making a play.

Examples of obstruction in baseball

Obstruction has been called in some pretty big moments. These calls have either affected or directly changed the outcome of the game. 

One of the most popular obstruction calls was in the World Series. In Game 3 of the 2013 World Series, the Red Sox were playing the Cardinals. In a tie game in the bottom of the 9th inning, the third baseman for the Red Sox obstructed a runner from scoring the winning run. He was called out at home, but the call ruled the runner safe. The Cardinals won the game on this play. 

It seemed as though this was the right call, as the fielder seemed to trip the runner after he fell down. He put his legs up in the air, which caused the runner to trip. 

Although there was much criticism of the call, it seemed to be the right one. The umpire decided that the only reason the runner was out at home was that he was obstructed.

Consequences of obstruction

During an obstruction call, there are a couple of different outcomes. All of them are decided upon by the umpire and the given situation. 

If a runner is more than halfway to a base and is obstructed, the umpire will allow the runner to advance to the next base past the one he was almost at. If the runner is almost at third base and would have easily scored, the run will be counted. 

A runner can also be called out if he interferes with a fielder when he is attempting to make a play. However, this is called interference instead of obstruction.

Frequently Asked Questions

What’s the penalty for obstruction?

When an obstruction is called, the runner is granted an extra base. He is also called safe if he was previously called out.

Can obstruction by a batter be ignored?

A catcher can obstruct a batter when he is swinging. This is called “catcher’s interference.”

Can the first baseman obstruct a runner?

Yes, the 1B can either block the base or make contact with the runner in an unnecessary way. In this situation, the runner will be ruled safe at first.

Is obstruction an error?

No, obstruction is not ruled an error.

What is the difference between interference and obstruction in baseball?

Interference occurs when the runner interferes with the fielder. He cannot make contact with a fielder while he is attempting to field the ball. If he does, he will be called out. Obstruction is when a fielder interferes with a runner. In this case, the runner will be ruled safe and granted an extra base.


Obstruction and interference can be easily confused. An easy way to remember it is that obstruction is a violation of the defense, while interference is a violation of the offense. 

While there is a specific rule, this call usually comes down to the umpire’s judgment. Sometimes they will allow contact to be made if it does not affect the outcome of the play. It depends on the umpire and his view of the rule. 

Understanding obstruction is essential for baseball players of all levels. Once you gain a complete understanding of these types of rules, you will gain a greater appreciation for the game of baseball.

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