The Commissioner's Office has issued the following Universal Ground Rules for use in all Major League ballparks this season. Ground Rules specific to Nationals Park follow the Universal Ground Rules below.
Universal Ground Rules
Ball on the top step (lip) of the dugout is in play.
No equipment is permitted to be left on the top step (lip) of the dugout. If a ball hits equipment left on the top step it is dead.
A player is not permitted to step or go into a dugout to make a catch.
A player is permitted to reach into a dugout to make a catch. If a player makes a catch outside the dugout and the player's momentum carries him into the dugout, then the catch is allowed and the ball remains alive as long as the player does not fall while in the dugout. See Rule 6.05(a).
A batted ball in flight can be caught between or under railings and around screens.
A catch may be made on the field tarp.
Batted or thrown ball lodging in the rotating signage behind home plate or along first base or third base stands is out of play.
Batted or thrown ball resting on the rotating signage behind home plate or along first base or third base stands is in play.
The facings of railings surrounding the dugout and photographers areas are in play.
Any cameras or microphones permanently attached on railings are treated as part of the railings and are in play.
Any recessed railings or poles that are in the dugout and photographers areas are out of play and should be marked with red to mark them out of play.
Robotic cameras attached to the facing of the backstop screen are considered part of the screen.
A batted ball striking the backstop camera is considered a dead ball.
A thrown ball striking the backstop camera is considered in play.
A ball striking the guy wires that support the backstop is a dead ball.
A ball lodging behind or under canvas on field tarp is out of play.
A ball striking the field tarp and rebounding onto the playing field is in play.
No chairs can be brought out of the dugout or bullpen and onto the playing field.
All yellow lines are in play.
Nationals Park Ground Rules
OUTFIELD AREA - LEFT FIELD
Fair bounding ball striking above the padded outfield wall between the vertical yellow line in foul territory and the left field foul pole is out of play: Two Bases.
Fair bounding ball striking above the padded outfield wall on or to the left of the vertical yellow line in foul territory is in play.