Obstruction vs Interference in Baseball: The Difference

Busch Stadium, St. Louis, the bottom of the ninth in Game 3 of the 2013 World Series. The score was tied, a throw to third had skipped away, and Allen Craig, getting up to run home, stumbled over Boston third baseman Will Middlebrooks, who was lying on the infield dirt with his legs in the air. Craig was thrown out at the plate. The run counted anyway, and the Cardinals won 5-4, because third-base umpire Jim Joyce had already pointed at Middlebrooks and called obstruction.

That play is the cleanest illustration of the difference. Obstruction is something the defense does to a runner. Interference is something the offense does to the defense. In Major League Baseball, obstruction (Rule 6.01(h)) is a fielder who does not have the ball and is not fielding it getting in a runner's way, and the penalty is bases awarded to the runner. Interference (mostly Rule 6.01(a)) is a batter, runner, coach or anyone on the offensive side hindering a fielder trying to make a play, and the penalty is usually an out, a dead ball and every other runner sent back. One rule gives bases. The other takes outs.

Obstruction vs interference in baseball: who commits which

The words sound interchangeable and the rulebook treats them as opposites. The Official Baseball Rules, the code that governs MLB and the affiliated minor leagues, define them in its "Definitions of Terms" and then deal with them in different places, and the cleanest way to keep them apart is to ask which team the offending player belongs to.

If the player in the way is wearing a glove, the call is obstruction. If he is wearing a batting helmet, or a base coach's windbreaker, the call is interference. Catcher's interference is the one exception to the naming, and it is a defensive foul that happens to carry the other word; it has its own detailed page on the catcher's interference rule and the manager's option.

The penalties point in opposite directions because the harm runs in opposite directions. A fielder who obstructs has cost a runner time or a base, so the umpire hands back what was taken. An offensive player who interferes has cost the defense a chance at an out, so the umpire takes the out himself and freezes everyone else.

	Obstruction	Interference (offensive)
Committed by	A fielder	A batter, runner, base coach or other offensive player
Victim	A runner	A fielder making a play, or a thrown or batted ball
Intent required	No	Usually no; some forms (the double-play rule) require it
Usual penalty	Runner awarded one or more bases	Offending player out, ball dead
Other runners	Awarded the bases the umpire judges they would have reached	Return to the last base legally touched, in most cases
MLB rule	6.01(h)	6.01(a), 5.09(b)(3), 6.03(a)(3)

Intent is mostly beside the point

On both sides of the line, the rule asks what happened rather than what the player meant. A shortstop who drifts into a runner's path while watching a ball in the outfield has obstructed even if he never saw the runner. A runner who collides with a second baseman fielding a grounder has interfered even if he was trying to get out of the way. The exceptions, where intent is written into the rule, are the willful interference that breaks up a double play and a few specific acts by a batter-runner. Everywhere else the call is about contact and effect.

College baseball under the NCAA rules book and high school under the National Federation of State High School Associations use the same two words with broadly the same split, but they differ on details such as the force-play slide rule and how malicious contact is penalized. This page describes the professional code unless it says otherwise.

What obstruction means under Rule 6.01(h)

The definition is one sentence long: obstruction is the act of a fielder who, while not in possession of the ball and not in the act of fielding the ball, impedes the progress of any runner. Every word of it does work.

"Not in possession of the ball" is the first escape hatch. A fielder holding the ball can stand anywhere he likes, including squarely on the base path, because he is about to make a tag and a runner has no right to run through him. "Not in the act of fielding the ball" is the second. A fielder going after a batted ball, or set to receive a throw that is coming directly to him, is entitled to the space he needs. "Impedes" is the trigger. It does not require contact, only that the runner's progress was hindered; a runner who has to swerve around a first baseman standing on the inside of the bag on a double down the line has been obstructed without anyone touching anyone.

What "the act of fielding" covers

The protection is narrower than a television replay sometimes makes it look. A comment to the rule says that once a fielder has made an attempt to field a ball and missed it, he is no longer in the act of fielding it. That is the clause that decided the 2013 World Series game. Middlebrooks dove for a throw, the ball went past him, and from that instant he was simply a body on the base path without the ball.

For thrown balls the comment is specific: a fielder about to receive a throw may be considered in the act of fielding if the ball is in flight directly toward him and near enough that he has to occupy his position to catch it. A first baseman stretching for a throw that is on its way is protected. A catcher setting up in front of the plate while the ball is still in the outfielder's glove is not. The difference between those two is the whole argument on most close plays.

A fielder is not a statue

No fielder is required to vanish. A shortstop retreating to cover second or a first baseman holding a runner stands near somebody's path, and presence alone is not obstruction. The umpire asks whether the fielder's position or movement hindered the runner, and that judgment is why ordinary obstruction is not reviewable on replay.

Type A and Type B obstruction: two penalties for one foul

The rulebook splits obstruction into two procedures, and umpires still teach them under the old labels Type A and Type B, from the days when they were sections (a) and (b) of the rule.

When a play is being made on the obstructed runner

If a play is being made on the obstructed runner, or if the batter-runner is obstructed before he reaches first base, the umpire calls "time" immediately. The ball is dead the instant obstruction occurs. The obstructed runner is awarded at least one base beyond the last base he had legally touched, and every other runner is placed where the umpire judges he would have ended up without the obstruction.

The classic case is a rundown. A runner caught between second and third, chased back and forth, collides with an infielder who has just thrown the ball and has not got out of the way. A play was being made on that runner, so the ball is dead and he goes to third. The other classic is a batter-runner who bumps into a first baseman standing in the base line without the ball while he is running out a ground ball; he is awarded first base.

When no play is being made on him

If no play is being made on the obstructed runner, the umpire signals the obstruction by pointing at it but does not stop play. Everything continues to its natural end. Then the umpire calls time and imposes whatever penalty, in his judgment, nullifies the act of obstruction. He might award the runner the next base, or two bases, or nothing at all if the runner would have stopped where he stopped.

A runner obstructed in this way who is then put out before reaching the base the umpire would have protected him to is called safe at that base. A runner who tries to go beyond it does so at his own risk; he gets no protection past the point the obstruction cost him.

1. 1Obstruction occursA fielder without the ball, and not fielding it, impedes a runner.
2. 2Was a play being made on him?If yes, or if the runner is a batter-runner short of first base, the ball is dead immediately.
3. 3Immediate awardThe obstructed runner gets at least one base beyond the last base he legally touched; others go where the umpire judges they would have gone.
4. 4No play on himThe umpire points at the obstruction and lets the action continue until play stops.
5. 5Time is calledThe umpire places every runner where the obstruction would not have mattered.
6. 6Protection limitA runner put out short of his protected base is safe there; past it, he runs at his own risk.

The two procedures in MLB Rule 6.01(h). The umpire, not the replay center, judges which applies and what each runner would have reached.

The second procedure is the one that confuses crowds, because the umpire may appear to do nothing for several seconds. He has seen it. He is waiting.

Game 3 of the 2013 World Series and the walk-off obstruction call

October 26, 2013. Cardinals and Red Sox tied 4-4 in the bottom of the ninth. Yadier Molina was on third base, Allen Craig on second, one out. Jon Jay hit a ground ball to second baseman Dustin Pedroia, who dove, stopped it and threw home to catcher Jarrod Saltalamacchia in time to cut down Molina for the second out.

Saltalamacchia then threw to third to try to get Craig, who had slid in. The throw was wide of the bag and got past Middlebrooks, who had dived for it and landed on the ground on the home-plate side of the base. Craig got up to run home, and his legs caught Middlebrooks' legs, which were raised as the third baseman lay there. Craig fell, got up, and ran. Left fielder Daniel Nava's throw home beat him and Saltalamacchia tagged him. Home-plate umpire Dana DeMuth looked at Joyce, saw the obstruction signal, and ruled Craig safe. The game was over.

1. 1Ground ballWith runners on second and third and one out, Jon Jay grounds to Dustin Pedroia.
2. 2Out at homePedroia throws home and Molina is tagged out for the second out.
3. 3Throw to thirdSaltalamacchia throws to third to catch Craig; the throw gets past a diving Middlebrooks.
4. 4The tripCraig, starting for home, trips over the third baseman lying in the base path.
5. 5Obstruction signaledJim Joyce points at Middlebrooks: no play was being made on Craig at that moment.
6. 6Award at homeCraig is tagged out at the plate, but DeMuth awards him home, the base the obstruction cost him.

The sequence as the umpires ruled it at Busch Stadium on October 26, 2013. It was the first World Series game to end on an obstruction call.

Why the lack of intent did not matter

The Red Sox' complaint afterward was understandable and wrong. Middlebrooks had not tried to trip anyone. He had dived for a ball, missed it, and had nowhere to go. The umpires' answer, given in the press conference that night by crew chief John Hirschbeck and Joyce, was the rulebook's: intent is not part of the definition, and once the ball had passed him Middlebrooks was no longer in the act of fielding it. He did not have the ball. He impeded the runner. That is obstruction, and the rule does not ask whether he could have avoided it.

It was the right call and an awkward one. A third baseman who has just dived and landed has a second or less to get out of the way, and the rule gives him no allowance for that, because the alternative would put the burden on the runner, who did nothing wrong at all.

Note what kind of obstruction it was. When Craig tripped, the ball was rolling away toward left field and nobody was making a play on him. So the umpires let the play finish, saw Craig thrown out, and then placed him where the obstruction would not have mattered: home plate.

Runner interference: the fielder's right of way on a batted ball

Turn the situation around. A ground ball is hit to the shortstop, a runner is going from second to third, and the shortstop has to move across the runner's path to field it. Who yields?

The runner does. A fielder attempting to field a batted ball has the right of way, and a runner who hinders him is out (Rule 5.09(b)(3) and Rule 6.01(a)). The ball is dead at the moment of interference. The batter-runner is awarded first base, and every other runner returns to the base he occupied at the time of the pitch unless the batter becoming a runner forced him to advance.

"Hinder" covers more than contact

The runner does not have to touch the fielder. Running across the fielder's line of sight close enough to distract him, pulling up in front of him, or waving his arms near a pop fly can all be interference. On the other side, a runner who runs past a fielder without changing direction, at a normal distance, has done nothing wrong even if the fielder then boots the ball. The umpire is judging whether the runner's conduct hindered the play, not whether the play failed.

Only one fielder is protected

When two fielders converge on the same ground ball and a runner collides with one of them, the umpire has to decide which fielder was entitled to field it. The rulebook protects only the fielder the umpire determines was entitled to field the ball. If the runner hits the other one, there is no interference, and depending on the circumstances there may be obstruction instead. It is a split-second judgment with no replay safety net.

The right of way flips once the ball is gone

The protection lasts while the fielder is attempting to field the batted ball. Once he has fielded it and thrown, or once he has missed it, he becomes an ordinary fielder without the ball. A shortstop who fields a grounder, throws to first and then stays planted in the base path where the runner from second is trying to go is now obstructing him. A fielder who dives, misses, and lies across the base line is in Middlebrooks' position.

Thrown balls are a different matter. A runner who is hit by a thrown ball has not interfered unless he did it on purpose; a throw that hits a runner is simply a live ball that bounced off something. The intentional version — a runner deliberately sticking out an arm to deflect a throw, or kicking a ball that is rolling past — is interference and he is out.

When a batted ball hits a runner

A runner standing a few feet off second base when a hard ground ball deflects off his ankle is out. That surprises some fans, who assume a ball that hits a runner is simply bad luck for everyone. The rule is direct: a runner is out when he is touched by a fair ball in fair territory before the ball has touched or passed an infielder (Rule 5.09(b)(7)). The ball is dead, the batter is awarded first base, and the official scorer credits the batter with a single.

The logic is protective of the defense. Had the ball not hit the runner, an infielder would have had a chance to field it. The runner occupied the space the ball was traveling through, and he pays for it with an out, even though he could not possibly have done anything to avoid a 100-mile-an-hour ground ball.

The exceptions

The rule only applies before the ball has touched or passed an infielder, and that is where the exceptions live.

• The ball has already passed an infielder. If a ground ball goes through or past an infielder and then hits a runner immediately behind him, the runner is not out, provided the umpire judges that no other infielder had a chance to make a play on it. The infield has had its chance. The ball stays live.
• The ball was deflected by a fielder. A ball an infielder has touched and deflected can then hit a runner without consequence, unless the runner did it intentionally.
• The runner is on his base and an infield fly hits him. If the infield fly rule has been declared and the ball touches a runner who is standing on his base, he is not out, though the batter still is. Off the base, he would be out along with the batter. Our explainer on the infield fly rule sets out when that call is made.
• Foul territory. The rule covers fair balls in fair territory. A runner hit by a ball while he is in foul territory, with the ball also foul, has not been put out by it.

The ball that gets by the pitcher

The awkward case is a ground ball up the middle that skips past the pitcher and hits a runner leading off second. The umpire's judgment does the work here. If the shortstop or the second baseman, playing behind the runner, still had a chance to field that ball, the runner who was hit cost them the play and he is out. The rule is protecting their chance, and it does not much matter that the ball had already gone by the man on the mound.

A batter hit by his own batted ball while still in the batter's box is a different case altogether. That is a foul ball, not an out, and the ball is dead. Out of the box and in fair territory, it is interference and he is out.

Batter interference with the catcher

A runner breaks for second with two strikes on the batter. The batter swings and misses, falls forward across the plate, and the catcher's throw sails into center field because the catcher had to throw around him. Interference.

Rule 6.03(a)(3) makes the batter out if he interferes with the catcher's fielding or throwing by stepping out of the batter's box or making any other movement that hinders the catcher's play at home base. The batter is the one called out. Runners return to the bases they occupied at the time of the pitch.

Out only if the throw fails

There is a qualification that keeps the penalty from becoming a gift. If the catcher's throw retires the runner anyway, the interference is disregarded. The defense got the out it was trying for, and the rule does not give it a second one. Only when the interference actually costs the defense something does the batter lose his turn.

When the runner was stealing home with fewer than two outs, the penalty shifts. The runner coming home is called out, not the batter, because that is the out the defense was trying to make. With two outs the batter is out instead, which ends the inning with the run off the board either way.

Backswing contact and incidental tangles

Two situations that look like interference are handled more gently. A batter who swings and, on the follow-through or backswing, unintentionally hits the catcher or the ball behind him is not called out for interference; the pitch counts as a strike only, the ball is dead and no runner may advance. And when a batter and catcher tangle in front of the plate — a catcher pouncing on a bunt, a batter starting for first — umpires generally treat it as incidental contact and call nothing, because both players are doing what they are entitled to do. The rulebook's comment says that contact between a catcher fielding the ball and a batter-runner heading to first is generally no violation, and that obstruction by a fielder attempting to field a ball should be called only in very flagrant cases. Most of it is not.

The batter is also entitled to his box. A batter who stays in the box and does not move is not required to vanish so the catcher can throw. A catcher who chooses to throw through a stationary batter has not been interfered with. Leaning over the plate, stepping toward the catcher, or making a movement that blocks the throw is what crosses the line.

Breaking up the double play: willful interference and the 2016 slide rule

Two outs for one act. That is the penalty when a runner willfully and deliberately interferes with a fielder in order to break up a double play: the runner is out for the interference, and the umpire also calls out the batter-runner, on the reasoning that the double play is what the runner set out to prevent. It is one of the few places in the rulebook where intent is part of the offense, and it is the oldest of the anti-takeout provisions.

For decades it was barely enforced. Runners going into second on a ground ball were expected to slide hard at the pivot man, and middle infielders learned to turn two while jumping a spike. Then came Game 2 of the 2015 National League Division Series, when Chase Utley of the Dodgers slid late, at the fielder rather than the bag, into Mets shortstop Ruben Tejada, and the league wrote a rule for 2016 that took the judgment of intent out of the most common version of the play.

What a bona fide slide requires

Rule 6.01(j) defines a "bona fide slide" on a force play at a base. The runner must:

• begin his slide, making contact with the ground, before he reaches the base;
• be able and attempt to reach the base with his hand or foot;
• be able and attempt to remain on the base after the slide is complete (home plate is excluded from this one); and
• slide within reach of the base without changing his path for the purpose of initiating contact with a fielder.

A runner who meets all four is protected even if he makes contact with the fielder. A runner who does not, and who makes contact or attempts to make contact with a fielder, has interfered under the rule. The penalty is the double-play penalty: the runner and the batter-runner are both out. A roll block, or a leg kicked up above the fielder's knee, is named outright as a violation.

Runner hinders fielder on a batted ball1outs

Batter blocks catcher's throw that fails1outs

Runner violates the 2016 slide rule2outs

Willful interference to stop a double play2outs

Outs charged by the umpire for the interference itself under MLB rules. Other runners are usually returned to their bases; outs already made on the play stand.

Show the numbers

Outs called for common offensive interference calls

Item	Value
Runner hinders fielder on a batted ball	1outs
Batter blocks catcher's throw that fails	1outs
Runner violates the 2016 slide rule	2outs
Willful interference to stop a double play	2outs

What the rule changed and what it did not

The rule made the takeout slide at second base a reviewable violation rather than a matter of etiquette, and it made it more expensive than a strikeout. What it did not do is protect a fielder who sets up in the base path himself. A shortstop who straddles the base and receives the throw in the runner's lane can still be slid into legally, provided the slide is bona fide. And a slide that meets the definition but still takes out the fielder because the fielder moved into it is legal.

The old "neighborhood play," in which a pivot man could turn a double play near second base without quite touching it, was the defense's side of the bargain under the old regime. It went the same year. The companion page on force outs and tag outs explains what replaced it.

Home-plate collisions and the 2014 rule

The catcher blocking the plate was, for most of baseball history, a defensive skill. Runners lowered a shoulder and ran through him; catchers set themselves and held on. In May 2011 the Giants' Buster Posey was injured in a collision at home, the conversation that followed did not die down, and for the 2014 season MLB and the players' union agreed a rule that became Rule 6.01(i).

It does two things, one aimed at each player.

The runner's half

A runner trying to score may not deviate from his direct pathway to the plate in order to initiate contact with the catcher, or with any player covering the plate. If he does, the umpire declares him out, even if the catcher drops the ball. The ball is dead and other runners go back to the last base touched at the time of the collision. A runner who slides into the plate properly, or who goes in standing up without leaving his line, has not violated the rule even if he makes contact.

The catcher's half

The catcher may not block the runner's pathway to the plate unless he is in possession of the ball. If the umpire judges that a catcher without the ball blocked the runner, the runner is called safe. In effect it is a specialized obstruction rule for the plate, with the same remedy: the base is awarded.

There is an exception for a catcher who is legitimately trying to field a throw. If he moves into the runner's path because the throw takes him there, or blocks the plate only in the course of a genuine attempt to catch the ball, there is no violation. A catcher who sets up in the lane before the throw arrives, with nothing to catch yet, is the target of the rule.

• 2014Home-plate collision rule
• 2014Manager challenges on replay
• 2016Bona fide slide rule at second base
• 2024Base-blocking emphasis on infielders

Season each provision first applied in Major League Baseball. Obstruction and interference themselves are far older and appear in the earliest professional codes.

Both halves can be reviewed on replay, which was a deliberate choice. The league wanted the rule enforced consistently, and a judgment made by the plate umpire through a cloud of dust was not going to achieve that alone.

Umpire, spectator, coach and catcher's interference

Four other kinds of interference appear in the rulebook. Each is narrow and each gets confused with the main two.

When the umpire is in the way

A plate umpire who hinders the catcher's throw on a steal or pickoff attempt has committed umpire's interference. If the throw still gets the runner, the out stands. If it does not, the ball is dead and runners return. A fair batted ball that hits an umpire before it touches or passes an infielder (other than the pitcher) is also umpire's interference: the ball is dead, the batter is awarded first base and credited with a hit, and runners advance only if forced. Once the ball has passed an infielder, an umpire is part of the field, the same as a pebble.

When a fan reaches over the wall

Spectator interference occurs when a fan reaches out of the stands or onto the field and touches a live ball. The ball is dead and the umpire imposes whatever penalties he judges would nullify the act, which can include ruling a batter out on a fly ball the fielder would have caught. Fans are entitled to catch a ball in the stands. A fielder who reaches into the seats does so at his own risk.

The most famous example is a call that was not made: Game 1 of the 1996 American League Championship Series at Yankee Stadium, when a 12-year-old named Jeffrey Maier reached over the right-field wall and pulled in a Derek Jeter fly ball that Orioles right fielder Tony Tarasco was waiting for. Umpire Rich Garcia ruled it a home run. There was no replay then. There is now, and spectator interference is reviewable.

When the coach helps

A base coach may not physically assist a runner in returning to or leaving a base. A third-base coach who grabs a runner rounding third and pushes him back has interfered, and the runner is out. A third-base coach who leaves his box and acts to draw a throw from a fielder can also be called for interference, and the penalty falls on the runner he was trying to help.

Catcher's interference, the defensive one

When the catcher's glove touches the bat during a swing, the batter is awarded first base. That foul is committed by a fielder, against the batter, and is penalized with a base rather than an out, so in substance it sits on the obstruction side of the line despite the name. The manager of the batting team can choose to take the result of the play instead of the award, which matters when the batter hit a double through the interference. The detail lives on its own page.

Which obstruction and interference calls replay can review

Most of the calls on this page are judgment calls, and judgment calls stay on the field. Whether a fielder was in the act of fielding a ball, whether a runner hindered him, whether an obstructed runner would have reached third or stopped at second: none of that is sent to the replay operations center in New York. The MLB replay review rules page lists the categories in full.

The exceptions are the newer contact rules, which the league made reviewable from the start.

Call	Reviewable in MLB?
Ordinary obstruction (Rule 6.01(h))	No; umpire's judgment
Runner interference with a fielder	No; umpire's judgment
Batter interference with the catcher	No
Home-plate collision rule (6.01(i))	Yes
Slide rule at second base (6.01(j))	Yes
Spectator interference	Yes
Catcher's interference	Depends on the season's regulations

A hedge worth stating

The list of reviewable plays is set out in the league's Replay Review Regulations rather than in the Official Baseball Rules, and MLB amends it before many seasons. Catcher's interference does not appear on the public summaries of the challengeable list that this desk could check, which is why the table above does not give it a flat answer. Anyone settling an argument about a specific season should use that season's regulations, because a claim that was true in 2016 may not have been true in 2014 or after a later revision.

When a reviewable call is overturned, the replay official also places runners. On a slide-rule violation that is straightforward, since the rule fixes the penalty at two outs. On a collision overturn the runner's status changes and other runners are returned or advanced as the regulation directs. Placing runners after a reviewed obstruction is not something replay does, because ordinary obstruction is not reviewed in the first place.

Recent tightening: base blocking in 2024 and the runner who seeks contact

The newest front in this rule is not home plate or second base on a double play. It is a middle infielder or third baseman taking a throw on a stolen base or a pickoff, dropping a knee in front of the bag before the ball arrives, and letting the runner's hand or foot hit the leg instead of the base.

For years that technique crept in. The rule never allowed it, since a fielder without the ball who impedes a runner has obstructed him, but it was rarely called because the throw arrived a split second later and the act looked like part of receiving it. For 2024 MLB told umpires to enforce the obstruction rule strictly on infielders who block a base without the ball, applying the same standard that already governed catchers at home. The penalty is the ordinary obstruction award: the runner is safe at the base. A fielder may still block a base once he has the ball, or while he is genuinely in the act of catching a throw that takes him into the path; what is out is the leg placed in the lane in anticipation.

The other side of the bargain

Any rule that rewards contact invites players to seek it. A runner who sees an infielder near the base can steer into him to manufacture an obstruction call, and the 2024 emphasis made that tempting. The answer sits in the definition itself: obstruction requires that the fielder impeded the runner, and a runner who steers out of his path to hit a fielder has not been impeded by anyone. Umpires can decline the call on that ground, and the runner who goes looking for a fielder is also exposed to an interference ruling if the fielder was making a play. Whether the league has since written a more specific penalty for contact-seeking runners into the rulebook is a matter for the current edition of the Official Baseball Rules; this page does not rely on one, and how strictly any such wording is applied will be settled by cases more than by text.

Where that leaves the line

Put together, the recent changes push both sides out of the lane. The fielder may not block without the ball. The runner may not aim for the fielder. Contact that results from both players doing what they are entitled to do is still incidental and still not a violation. That is the same principle the 2014 and 2016 rules applied at home plate and second base, extended around the infield.

No camera will ever call these. Both turn on what a fielder was doing at one instant, and umpires decide that in real time. The baseball section of the site collects the sport's other rules, and the page on appeal plays for missed bases and leaving early covers the calls the defense has to ask for before an umpire will make them.