Rules of Golf

Golf Rule 19 - Ball in Motion Deflected or Stopped

BALL IN MOTION DEFLECTED OR STOPPED: I receive more questions from around the world about this rule than any other.

Ball in motion deflected or stopped by an Outside Agency (rub of the green)--if a ball in motion is accidentally deflected or stopped by any outside agency (an agency that is not part of the competition), the ball must be played as it lies without penalty.
NOTE--other than a stroke made from the putting green, any ball in motion after a stroke that comes to rest in or on any moving outside agency must drop the ball as near as possible to the spot where the outside agency was when the ball came to rest.
NOTE--on the putting green, if a ball in motion after a stroke is deflected or stopped, or comes to rest in or on any moving outside agency (other than an insect or the like)the stroke must be cancelled and the ball replaced and the stroke replayed without penalty. Another ball may be substituted in the original ball is not immediately recoverable.
NOTE--if the Committee or referee determines that a player's ball has been stopped or moved on purpose by an outside agency (such as a spectator)a decision should be made based on equity and common sense. A disqualification or an exerting influence penalty may be applied at the Committees discretion if the outside agency that deflected or stopped the ball on purpose was a fellow competitor or the fellow competitor's caddie.

Ball in motion accidentally deflected or stopped by The Player, Partner, or Either of Their Caddies or Equipment--in Match Play the penalty is Loss of Hole.
In stroke play the penalty to the player is two strokes, and the ball must be played at lies. If the ball comes to rest in or on any of the competitor's sides clothing or equipment through the green or in a hazard, the player must drop the ball, or on the putting green place the ball as near as possible to where the ball came to rest.
NOTE--a ball deflected or stopped on purpose is subject to a penalty of disqualification or exerting influence by the Committee.

Ball in motion accidentally stopped or deflected by Opponent or Opponent's Caddie or Equipment--in Match Play there is no penalty, (this option can make the difference in a match) the player has the option of playing the ball as it lies, or can (before another stroke is played by either side) play another ball without penalty as nearly as possible at the spot from which the original ball was last played.
NOTE--If the player's ball comes to rest in or on the opponent's sides clothes or equipment, through the green or in a hazard drop the ball, or on the putting green place the ball as nearly as possible to where the ball came to rest.
NOTE--if deflected or stopped on purpose, the penalty of exerting influence or disqualification may be applied by the Committee.
NOTE--an exception to this rule is when a person is attending the flagstick.

Ball in motion deflected or stopped by Another Ball--if another ball is at rest and the player's ball is in motion, the player plays his ball as it lies, and the other ball at rest that moved must be replaced. In match play there is no penalty if this occurs. However, in stroke play there would be a penalty to the player (two-strokes)if both balls are on the putting green prior to the stroke.
If both balls are in motion the balls are to be played as they lie when they come to rest without penalty. A penalty would only occur if the other ball was not an outside agency (loss of hole in match play, and two-strokes in stroke play) and if it was not the player's turn to play and he played his stroke while the other ball was in motion after a stroke from the putting green.