When a fielder does not have the ball and is not in the act of fielding a batted ball, an obstruction occurs if that fielder impedes the progress of a base runner. The umpire makes an obstruction signal by extending the left arm to the side with a fist. If the impeded runner is put out prior to reaching the next base or a subsequent base that the umpire believes she would have reached if the obstruction had not occurred, then the out does not count and the umpire will put the runner on the base she would have reached absent the obstruction.
