Major League Baseball will implement a new experimental rule in 2014 to prohibit most egregious collisions at home plate.
According to MLB, the new rule sets forth that "a runner attempting to score may not deviate from his direct pathway to the plate in order to initiate contact with the catcher (or the player covering home plate). If, in the judgement of the Umpire, a runner attempting to score initiates contact with the catcher (or the player covering home plate) in such a manner, the Umpire shall declare the runner out (even if the player covering home plate loses possession of the ball)."
The rule also sets forth that "unless the catcher is in possession of the ball, the catcher cannot block the pathway of the runner unless he is attempting to score. If, in the judgement of the Umpire, the catcher, without possession of the ball, blocks the pathway of the runner, the Umpire shall call or signal the runner safe."
The rule aims to reduce the number of serious injuries at home plate, especially with concussion awareness at the forefront of the player safety debate. It is unclear if MLB will continue to implement the rule beyond 2014.