Players are familiar with the "three strikes and you're out" rule. However, when the third strike is dropped by the catcher, the batter is not automatically out. The Amateur Softball Association defines the rules for a dropped third strike. The ruling depends on the number of outs, the location of the base runners, and the batter's recognition of the situation and her ability to react to the play.
The Amateur Softball Association defines the dropped third strike rule in Rule 8, Section 1B: "When the catcher fails to catch the third strike before the ball touches the ground and there are fewer than two outs and first base is not occupied at the time of the pitch or any time there are two outs." If the batter does run, the catcher must throw her out at first to complete the out.
Fewer than Two Outs
The batter can try to run to first if there's no runner there and her team has less than two outs. If a runner is on first, and the batting team has no outs, or only one out, a dropped third strike is automatically an out.
With two outs, the batter can run to first on a dropped third strike even if a teammate is already on first base. That's because the dropped ball is considered live, and the defensive team can try to force an out at any base.
It is not always easy to see that the ball has not been caught, as it happens directly behind the batter. The batter must instantly recognize the drop and run to first. Base runners also need to be aware of the number of outs, as well as the pitch count, as they will need to decide whether to advance or stay safely on their current base.