• Obstruction is a violation by the defense: a fielder impedes a runner

Rule 7.06

• Fielders who are not actively involved in a play must give way to runners.
• There is no "intent" clause anywhere in the OBS rules
• Even if a fielder causes a runner to change her path, OBS can be called. No contact needs to be made.

• "Type A" OBS
• A play is being made on a runner while he is obstructed
• This usually happens in a rundown
• Ball is dead, and obstructed runner gets at least one base--no matter which base she is head toward. See Case A, below.
• Type A OBS carries a mandatory award.

• Type "B" OBS (much more common)
• No play is being made on obstructed runner
• Umpire extends left hand outward, points to violation and says "That's obstruction." This is not a dead ball, Play on, Macduff.
• After all play has ceased, umpires will judge where runners should be placed as if the OBS had not occurred. See Cases below
• Type B OBS carries no mandatory award.

• Interference is a violation by offense: a runner prevents a fielder from doing his job
• The exception to this terminology is catcher's interference [6.08(c)], which should actually be called "catcher's obstruction."

Catcher's Interference: 6.08(c)

1. This occurs most often when the catcher tips the bat with is glove.
2. If no play follows the interference, umpires will kill the play, award batter 1B; other runners advance one base, if forced. Exception: if a play occurs where batter does not put the ball into play, AND R3 is trying to score on a squeeze or steal of home, the batter is awarded 1B, and R3 is awarded home.
3. If a play follows the INT, and batter plus all runners advance one base, no reference is made to the INT.
4. If, on such a play, such advances are not made, the defensive manager will have a choice of accepting the play as it stands, OR take the INT award as in (2) above.

Interference by a Runner

1. See rule7.09 for a variety of ways that INT can occur.
2. The defense always has the right of way when the situation involves a batted ball (see also 7.11).
3. INT on a thrown ball is an intentional act by a runner.
4. Yes, it can be INT on a runner if she is hit by a batted ball--see details in 7.09(k).
5. On 7.09 calls, the batter or runner is out, and the ball is dead. Runners return to prior legally touched base.

OBS CASES
Case A Situation: In a rundown between 3B and HP, R3 is diving back to 3B and is obstructed by F5 as F2 puts the tag on R3.
Outcome: Umpires call immediate dead ball and award R3 home.

Case B Situation: B1 hits a long gapper. As he rounds 1B, F3 is standing on the base, causing B1 to change his path. B1 slides into 2B and beats F4's tag.
Outcome: This is Type B OBS by F3; he had no play on B1, so cannot be standing on the base. Umpire calls delayed dead ball, but since B1 made 2B safely, no award is given.

Case C Situation: As R2 heads toward 3B, he is obstructed by F6. R2 tries for home, and is tagged before he reached HP on a close play by F2.
Outcome: Delayed dead ball at point of OBS. As the tag is applied by F2, umpire calls time and awards R2 HP.

Case B Situation: R2 only; no outs. B1 attempts bunt and F2 interferes. B1 is retired at 1B. R2 advances to 3B.
Outcome: After play phase, offensive manager can "take the play," meaning R2's advance is allowed, and B1's out goes into the book -- OR-- manager can take the interference, putting B1 on 1B and keeping R2 at 2B, with no out recorded.

Case C Situation: In a rundown between 3B and HP, R3 waves his arms in F2's face and strikes the thrown ball.
Outcome: R3 is called out; any other runners must return to their last legally achieved base at the time of the INT.

Case D Situation: R1, 1 out. B1 grounds to F4, who forces R1. R1 then continues to run at F4, waving his arms, preventing a throw from F4 to F3.
Outcome: R1 is already out, so he has violated 7.09(e). B1 is also called out.