(a) Offensive interference is an act by the team at bat which interferes with, obstructs, impedes, hinders or confuses any fielder attempting to make a play. If the umpire declares the batter, batter-runner, or a runner out for interference, all other runners shall return to the last base that was in the judgment of the umpire, legally touched at the time of the interference, unless otherwise provided by these rules.
Rule 2.00 (Interference (a)) Comment: In the event the batter-runner has not reached first base, all
runners shall return to the base last occupied at the time of the pitch.
(b) Defensive interference is an act by a fielder that hinders or prevents a batter from hitting a pitch.
(c) 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.
Rule 2.00 (Interference (c)) Comment: Umpire interference may also occur when an umpire interferes with a catcher returning the ball to the pitcher.
(d) Spectator interference occurs when a spectator reaches out of the stands, or goes on the playing field, and (1) touches a live ball or (2) touches a player and hinders an attempt to make a play on a live ball.
On any interference the ball is dead.
"On any interference the ball is dead" is true, except for catcher's interference, batter's interference, and umpire interference.
Fan reaches out of the stands and interferes with a catchable fly ball over live ball territory without touching player. Umpire incorrectly rules a home run.