6.03 (a) (6.06) A batter is out for illegal action when:
(1) He hits a ball with one or both feet on the ground entirely outside the batter’s box.
Rule 6.03(a)(1) Comment (Rule 6.06(a) Comment): If a batter hits a ball fair or foul while out of the batter’s box, he shall be called out. Umpires should pay particular attention to the position of the batter’s feet if he attempts to hit the ball while he is being intentionally passed. A batter cannot jump or step out of the batter’s box and hit the ball.
(2) He steps from one batter’s box to the other while the pitcher is in position ready to pitch;
(3) He interferes with the catcher’s fielding or throwing by stepping out of the batter’s box or making any other movement that hinders the catcher’s play at home base.
(4) He throws his bat into fair or foul territory and hits a catcher (including the catcher’s glove) and the catcher was attempting to catch a pitch with a runner(s) on base and/or the pitch was a third strike.
EXCEPTION to Rules 6.03(a)(3) and (4): Batter is not out if any runner attempting to advance is put out, or if runner trying to score is called out for batter’s interference.
Rules 6.03(a)(3) and (4) Comment (Rule 6.06(c) and (d) Comment): If the batter interferes with the catcher, the plate umpire shall call “interference.” The batter is out and the ball dead. No player may advance on such interference (offensive interference) and all runners must return to the last base that was, in the judgment of the umpire, legally touched at the time of the interference.
If, however, the catcher makes a play and the runner attempting to advance is put out, it is to be assumed there was no actual interference and that runner is out—not the batter. Any other runners on the base at the time may advance as the ruling is that there is no actual interference if a runner is retired. In that case play proceeds just as if no violation had been called.
If a batter strikes at a ball and misses and swings so hard he carries the bat all the way around and, in the umpire’s judgment, unintentionally hits the catcher or the ball in back of him on the backswing, it shall be called a strike only (not interference). The ball will be dead, however, and no runner shall advance on the play.
(5) He uses or attempts to use a bat that, in the umpire’s judgment, has been altered or tampered with in such a way to improve the distance factor or cause an unusual reaction on the baseball. This includes bats that are filled, flat-surfaced, nailed, hollowed, grooved or covered with a substance such as paraffin, wax, etc.
No advancement on the bases will be allowed (except advancements that are not caused by the use of an illegal bat, e,g., stolen base, balk, wild pitch, passed ball), and any out or outs made during a play shall stand. In addition to being called out, the player shall be ejected from the game and may be subject to additional penalties as determined by his League President.
Rule 6.03(a)(5) Comment (Rule 6.06(e) Comment): A batter shall be deemed to have used or attempted to use an illegal bat if he brings such a bat into the batter’s box.