However, on a uncaught 3rd strike that is to the right of the 1B foul line, the defender, and BR, may use either side of the double base.
ISF Rule 2.4.h.1
NOTE: THE FOLLOWING RULES APPLY TO THE DOUBLE BASE:
a) A batted ball hitting the fair portion is declared fair, and a batted ball hitting the foul portion only is declared foul.
b) If a play is made at first base on any batted ball, or (FP ONLY) the batter runs on a dropped third strike, and the batter-runner touches only the fair portion, and if the defense appeals prior to the batter-runner returning to the fair portion of first base, the batter-runner is out.
NOTE: This is treated the same as missing the base.
c) A defensive player must use only the fair portion of the base at all times.
EXCEPTION: On any live ball play made from first base foul territory, the batter-runner and the defensive player may use either base. When the defensive player uses the foul portion of the double base, the batter-runner can run in fair territory and if hit by a throw from the foul side of first base, it would not be interference. If intentional interference is ruled, the batter-runner would be out. NOTE: The one meter line is doubled on throws from foul territory.
d) After over-running the base, the batter-runner must return to the fair portion.
e) On balls hit to the outfield when there is no play being made at the double base, the batter-runner may touch either portion of the base.
f) When tagging up on a fly ball, the fair portion must be used.
g) On an attempted pick-off play (FP ONLY) the runner must return to the fair portion.
h) Once a runner returns to the fair portion, should he stand on the foul portion only, it is considered not in contact with the base and the runner shall be called out, if
1) He is tagged with the ball, or
2) He leads off from the foul portion on a pitched ball.
Thank you for that. We had it ruled as obstruction as she took the orange base and the ball hadn't gone 'far enough to the right' in the words of the umpire. The head chief (when we queried that rule later that day) said it was a brilliant decision and that the ball had to go further to the right. I might send her that on FB and get it clarified again.