• Interference is called when a batter impedes a defensive play.baseball image by Tomasz Plawski from Fotolia.com
  
  In baseball, an umpire may call batter interference if he determines that a batter has illegally impeded a defensive play, either decreasing the chances of an out or improving the odds of advancing a runner. The most common forms of batter interference occur when a batter runs outside the designated path between home plate and first base or when the batter hits the ball a second time or redirects it with his bat or helmet. Generally, if batter interference is called, the ball is considered dead, the batter is out, and any base runners must return to their previous positions. Major League Baseball rules outline when batter interference should be called.
  
  

Hitting the Ball Twice

• In MLB, a batter is considered out, the ball is dead, and no runners advance if a batter hits the ball a second time in fair territory. The umpire may also call interference if the entire bat is thrown in fair territory in the process of the swing and it interferes with a defensive player trying to make a play. There is an exception if the batter-runner drops the bat and the ball rolls against the bat in fair territory, and the umpire determines there was no intention to interfere with the baseball. Another exception is if a bat breaks and part of it falls into fair territory and is hit by a batted ball or if it hits a runner or fielder. In these cases, play should continue.
  
  

Leaving the Base Path

• After hitting the ball, batters who are running the last half of the distance between home plate and first base must stay in a designated base path. This 3-foot-wide path is marked on each side by the base line and a parallel white line in foul territory. The batter must stay in this path to prevent interference with the first baseman catching a throw at first base. Interference may be called if the batter runs to the right of the 3-foot-wide path, in foul territory, or to the left of the base line, in fair territory, and in doing so, interferes with the fielder taking the throw at first base. An exception is made when the batter runs outside the path to avoid a fielder attempting to field a batted ball.
  
  

Interfering with the Catcher

• The batter's box is a 4 by 6-foot box next to home plate where a player stands while batting. An umpire may call interference when a batter interferes with a catcher's fielding or throwing by stepping out of the batter's box or making any other movement that hinders a play at home plate. The ball is dead, the batter is out and all base runners must return to the last base that was, in the umpire's judgment, legally touched at the time of interference. If however, a catcher makes a play and the runner attempting to advance is put out, it is assumed that there was no actual interference. In that case, the runner is out, but the batter is not, and play will resume as if there was no violation.