Fans or spectators can also be called for interfering if they reach out of the stands or fall into the playing field, effectively impeding a fielder’s ability to make a play. In simple terms, this occurs when a fan – intentionally, unintentionally, or ignorantly – touches a live ball or touches a player and hinders his attempt to make a play on a live ball. When it occurs, the ball is ruled dead and outs are made or bases are awarded, as appropriate, to nullify the outcome of the interference. (Incidentally, the fan is usually removed from his seat by stadium personnel.)
The question about spectator interference is whether the fan reached into the field to interfere with the play. Fans are under no obligation to move from their positions in the stands to make room for a fielder attempting to make a play. So if a fielder reaches over a fence, railing, rope or into a stand to catch a ball, there is no interference. However, if a fielder reaches into the stands to make a catch, it is a legally caught ball. Before or after making the catch, the fielder can reach, leap or fall into the stands. If he is able to keep control of the baseball and show the umpire a voluntary release, it will be ruled a catch.
The same spectator interference rules apply to a thrown ball as a batted ball. If a thrown ball goes into the stands, the ball is already in dead ball territory so interference is not called.
Ted Barrett and Chris Welsh discuss the fine points of spectator interference.
Insider Report: Non-Player Interference
Spectator interference creates a dead ball and empowers the umpires to place batter and runners where they judge they would have reached had there been no interference. Read all about the nuances of this rule in this Insider Report.
Since umpires place runners where they think they would advance had no interference occurred, sometimes an umpire might award a runner home when the defensive manager feels like the runner would not have scored. Help yourself understand the rule by reading this Insider Report.
There are a few ways an umpire can interfere with a live ball or play in the field. If an umpire somehow impedes a catcher attempting to pick off a base stealer, the ball will be ruled dead and the runners will have to return to their time-of-pitch base(s). As mentioned earlier, this interference will be dismissed if the catcher ends up being able to complete his intended play anyway.
If an umpire is touched by a batted ball before it reaches a fielder, the ball is dead and no runners can advance or score. As a play in the field cannot be necessarily assumed, though, the batter will be awarded first base in this scenario.
If an umpire is touched by a batted ball before it passes a fielder (other than the pitcher), it is umpire interference.
Other Unintentional Interference [Official Rule 6.01(d)]
In its complexity and comprehension, baseball rules even mandate rules for interference regarding basically “anyone else” who might be at the ballpark. These (typically “unintentional”) interference parties could include on-field photographers, police offices, ball boys, or other employees of the home team. The umpire will take corrective action to nullify any result of a play where one of these groups comes in contact with a live ball.