Players may partially or completely cross the center line below the
net or outside the poles, either before, during or after a legal play
of the ball, provided that this does not interfere with the opponents
play. Incidental contact with an opponent is ignored, unless such
contact interferes with the opponents opportunity to play the ball.
While opposing players are not required to avoid the ball or the player,
they cannot intentionally interfere with any legal attempt to play the
ball on their court.If a player crosses the center line and interferes with an opponent
during the continuation of a play, it is a fault.