The most common type of catcher’s interference occurs when the batter swings and his bat makes contact with the catcher’s mitt. The batter becomes a runner and is entitled to first base without liability to be put out provided he advances to and touches first base when the catcher or any fielder interferes with him.
The Pitcher (or Catcher) Balks
When a balk is called, the ball is dead, and each runner shall advance one base without liability to be put out, unless the batter reaches first on a hit, an error, a base on balls, a hit batter, or otherwise, and all other runners advance at least one base, in which case the play proceeds without reference to the balk.
NOTE: For more explanation of balks and balk rules please refer to the Pitcher Infractions lesson.
An Umpire is Hit by a Batted Ball
If a batted ball touches an umpire before it touches a fielder, the batter is awarded first base.
KNOW THIS: When a ball deflects off the pitcher (or another infielder) and strikes the field umpire who is positioned in front of a fielder, the ball should remain alive and in play and no interference should be called.
An umpire located in the infield is struck by a batted ball.
Umpire Interference [Insider Report]
This Insider Report explains in detail how easily the Umpire Interference Rule can be misinterpreted and wrongly called by experienced umpires.
A Runner is Hit by a Batted Ball
If a batted ball touches a runner (not including the batter-runner) before it touches a fielder, the batter is awarded first base. However, the touched runner would be called out.
KNOW THIS: When a runner is judged to deliberately interfere with a batted ball with the obvious intent to break up a double play, the ball is dead and both the runner and batter-runner are called out per rule 7.09 (f). Of course, this is umpire judgment.
Baserunners Struck by Batted Ball [Insider Report]
Fielder Obstruction of the Batter-Runner
This normally occurs when the batter-runner is impeded before reaching first base by a pitcher covering the base, who does not have the ball and is not in the act of receiving a toss. If the batter-runner is obstructed before reaching first base with the ball in the infield, “Time” is called and he gets first base.