What is obstruction in baseball?
A · Advanced · Running the bases · 4 of 9Obstruction is the reverse of interference: a fielder who does not have the ball, and is not fielding it, gets in a runner's way. The runner is given the base they would have reached. If a play was being made on that runner, the ball is dead at once and they get at least one base.
How it works
- The definition: 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".
- Fielding counts: a fielder about to receive a throw that is close and on its way may be in the act of fielding.
- After a miss: a fielder who dives, misses and lies in the way is no longer fielding.
- Play on the runner: the ball is dead. Runners go to the bases they would have reached, and the obstructed runner gets at least one base.
- Common cases: a batter-runner blocked before first on a ground ball, and a runner blocked in a rundown.
- No play on the runner: play carries on. Afterwards the umpire awards whatever cancels the obstruction.
- Common cases: a batter-runner bumped rounding first on a hit, and a runner forced to change course by a fielder standing in the way.
- At their own risk: a runner who goes beyond the base they would have been given can be tagged out.
- The catcher: without the ball, the catcher has no right to block the runner's way to the plate.
- Blocking the view: a fielder may not deliberately block a runner's sight of a catch.
The glossary has the obstruction entry, the interference entry, the base runner, the infielders, the catcher and the tag out.
Tricky cases
In a rundown, a fielder who has thrown the ball a moment earlier stays in the line and the runner runs into them. What is the call?
Obstruction with a play being made on the runner. The ball is dead and the runner is awarded at least one base beyond the last one touched.
A batter hits to the outfield and collides with the first baseman while rounding first. The ball is still in the outfield. Is play stopped?
No. No play was being made on that runner, so play continues and the umpire then places the runner where they would have got to.
An obstructed runner is awarded third in the umpire's mind but keeps going for home and is tagged. Out?
Yes. A runner who advances beyond the base they would have been awarded does so at their own peril.
The catcher stands in the baseline waiting for a throw that has not arrived, and the runner has to slow down. Obstruction?
Yes, unless the catcher was in the act of fielding the throw. Without the ball the catcher has no right to block the pathway.
Why the rule exists
The fielder has the right of way to the ball and the runner has the right of way to the base. Obstruction protects the second of these. Without it a fielder could stand in the line, take the collision and wait for a team-mate to bring the ball.
Where it differs
| Where | What changes | Source |
|---|---|---|
| A play is being made on the obstructed runner | Ball dead; at least one base | WBSC Baseball Rule 12.7, Type A |
| No play on the obstructed runner | Play continues; umpire then awards bases | WBSC Baseball Rule 12.7, Type B |
| Batter-runner obstructed, but the fly ball is caught | Obstruction ignored | WBSC Baseball Rule 12.7 exception |
| Fielder with the ball | Not obstruction; the collision rule applies | WBSC Baseball Rule 12.8 |
From the rule book
World Baseball Softball Confederation, Official Rules of Baseball (2025-2026 edition), Rules 6.54 and 12.7. Checked 14 October 2026. Official document: WBSC Official Rules of Baseball 2025-2026 (PDF).