RULE 5.06(c)(2) - The ball becomes dead and runners return to their bases, without liability to be put out, when the plate umpire interferes with the catcher’s throw attempting to prevent a stolen base or retire a runner on a pick-off play; runners may not advance.

NOTE: The interference shall be disregarded if the catcher’s throw retires the runner. 

RULE 5.06(c)(2) Comment: Umpire interference may also occur when an umpire interferes with a catcher returning the ball to the pitcher.

RULE 5.06(c)(6) - The ball becomes dead when a fair ball touches an umpire before it has passed an infielder other than the pitcher; runners advance, if forced. If a fair ball touches an umpire after having passed a fielder other than the pitcher, or having touched a fielder, including the pitcher, the ball is in play.

RULE 5.06(b)(4) - The batter becomes a runner when... a fair ball touches an umpire or a runner on fair territory before touching a fielder.

RULE 6.01(f) - If a thrown ball accidentally touches a base coach, or a pitched or thrown ball touches an umpire, the ball is alive and in play. However, if the coach interferes with a thrown ball, the runner is out.

Rule 6.01(f) Comment: Umpire’s interference occurs (1) when a plate umpire hinders, impedes or prevents a catcher’s throw attempting to prevent a stolen base or retire a runner on a pick-off play; or (2) when a fair ball touches an umpire on fair territory before passing a fielder. Umpire interference may also occur when an umpire interferes with a catcher returning the ball to the pitcher.

RULE 6.01(a)(1) - If a pitch that is not caught remains in the vicinity of home plate and it is inadvertently deflected by the umpire, that ball is a dead ball and the runners should return to the bases they occupied at the time of the pitch (but if the pitch was strike three, the batter is out).