Rule 5-1-2b, 8-1-1e
If the catcher interferes with the batter’s swing:
The batter is awarded first base.
Any runners advance if forced.
If the batter still puts the ball in play, the offensive coach has the option to accept the result of the play or take the penalty.
If a runner is stealing home, and the catcher steps on or in front of home plate without the ball, it is obstruction, and the runner is awarded home plate.