In baseball, a sequence of nine players bat in order, taking turns in an attempt to become a runner and reach base or to help preceding runners to score. Occasionally, one or more batters may bat in the incorrect order, thus violating rule 6.01(a) in the Official Baseball Rules. This situation is called simply batting out of turn or batting out of order.
Batting out of turn is ignored by rule unless a member of the defensive team notifies the umpire that an infraction has occurred. Once the umpire is notified, he enforces the rule.
At any time, the proper batter is simply the player whose name follows the previous actual batter in the written batting order. Any batting out of turn situation is effectively legalized when the first pitch is thrown to a following batter. Thus, in order to determine who is the proper batter at any given time, it is necessary only to consider the last two batters who have received a pitch.
If an infraction is discovered immediately after a batter completes his appearance, then the umpire considers that batter and the previous one. If the batter who just finished batting does not follow the previous batter in the written order, his plate appearance was improper, his action is nullified (i.e. he is removed from the bases and his outs are cancelled), and the proper batter is called out.
If the infraction is discovered during a plate appearance (that is, a pitch has been thrown to the current batter), then the umpire considers the current batter and the previous one. If the current batter's name does not follow the previous batter's name in the written order, the current batter is improper. There is no penalty, but the situation is rectified--the proper batter comes to bat and assumes the improper batter's current count. In this situation, if the proper batter is on base, then he is simply skipped in the order, and the next batter in the order is now the proper batter.
Example 1:
Suppose the batting order is: Able, Baker, Charles, Daniel, Edward, Frank, George. Able bats and is put out. Edward then bats out of turn. Edward reaches first base, and Charles then comes to bat and reaches base. The infraction is discovered before a pitch is thrown to any subsequent batter. RULING: Edward did bat out of turn, but the first pitch to Charles legalized Edward's plate appearance. Therefore, the proper batter after Edward is Frank, so Charles is removed from the bases, Edward is returned to first base, Frank is called out for failing to bat in his proper turn, and George is now the proper batter.