19-1. If an outside agency hits a player’s moving ball, there is no penalty. (In general, an outside agency is anything other than a player, caddie, a ball in play on the hole or a player’s equipment.

Wind and water aren’t considered outside agencies.) The ball is played as it lies, unless it rests in or on a moving object or animal off the green; if so, it is dropped or placed as close as possible to the location where it rested on the outside agency (no nearer the hole).
If a putted ball is stopped or deflected by, or stops on, a moving outside agency, the player replays the stroke without penalty.

If a player’s ball is deliberately stopped or deflected by an outside agency anywhere but on the green, the player must estimate where the ball would have stopped. If that is through the green or in a hazard, the player drops as close as possible to the spot. If the ball would have gone out of bounds, the player proceeds under the stroke-and-distance penalty as though it did go OB. If on the green, the ball is placed as close to the spot as possible.

If a putted ball is deliberately stopped or deflected by an outside agency, the player replays the stroke from the original spot without penalty.

19-2. If a player, his partner, either of their caddies or equipment inadvertently stops or deflects his ball, he incurs a one-stroke penalty (match or stroke play) and plays the ball as it lies. If the ball is deliberately stopped or deflected, the player loses the hole (match play) or takes a two-stroke penalty (stroke play).

19-3. In match play, if a player’s opponent or opponent’s caddie inadvertently stops or deflects his ball, the player can either replay the shot from the same spot or play the ball as it lies. If the stopping or deflection was deliberate, the opponent loses the hole.

19-4. In stroke play, a ball deflected by a player’s competitor or their caddie generally results in a two-stroke penalty for the competitor, per Rule 1-2.

19-5. If a player’s ball in motion hits a ball at rest, he plays it as it lies. There’s no penalty unless both balls are on the green, in which case the player who hits the ball takes a two-shot penalty in stroke play (no penalty in match play).

If a player’s ball in motion hits another ball in motion (except on the green), he plays it as it lies without penalty. If this happens on the green, the player cancels the stroke and replays from the original position without penalty.

19-1. By Outside Agency
If a player’s ball in motion is accidentally deflected or stopped by any outside agency, it is a rub of the green, there is no penalty and the ball must be played as it lies, except:

a. If a player’s ball in motion after a stroke other than on the putting green comes to rest in or on any moving or animate outside agency, the ball must through the green or in a hazard be dropped, or on the putting green be placed, as near as possible to the spot directly under the place where the ball came to rest in or on the outside agency, but not nearer the hole, and

b. If a player’s ball in motion after a stroke on the putting green is deflected or stopped by, or comes to rest in or on, any moving or animate outside agency, except a worm, insect or the like, the stroke is canceled. The ball must be replaced and replayed.

If the ball is not immediately recoverable, another ball may be substituted.

Exception: Ball striking person attending or holding up flagstick or anything carried by him – see Rule 17-3b.

Note: If a player’s ball in motion has been deliberately deflected or stopped by an outside agency:
(a) after a stroke from anywhere other than on the putting green, the spot where the ball would have come to rest must be estimated. If that spot is:
(i) through the green or in a hazard, the ball must be dropped as near as possible to that spot;
(ii) out of bounds, the player must proceed under Rule 27-1; or
(iii) on the putting green, the ball must be placed on that spot.
(b) after a stroke on the putting green, the stroke is canceled. The ball must be replaced and replayed.

If the outside agency is a fellow-competitor or his caddie, Rule 1-2 applies to the fellow-competitor.

(Player’s ball deflected or stopped by another ball – see Rule 19-5)

19-2. By Player, Partner, Caddie Or Equipment
If a player’s ball is accidentally deflected or stopped by himself, his partner or either of their caddies or equipment, the player incurs a penalty of one stroke. The ball must be played as it lies, except when it comes to rest in or on the player’s, his partner’s or either of their caddies’ clothes or equipment, in which case the ball must through the green or in a hazard be dropped, or on the putting green be placed, as near as possible to the spot directly under the place where the ball came to rest in or on the article, but not nearer the hole.

Exceptions:1. Ball striking person attending or holding up flagstick or anything carried by him – see Rule 17-3b.
2. Dropped ball – see Rule 20-2a.

(Ball purposely deflected or stopped by player, partner or caddie – see Rule 1-2)

19-3. By Opponent, Caddie Or Equipment In Match Play
If a player’s ball is accidentally deflected or stopped by an opponent, his caddie or his equipment, there is no penalty. The player may, before another stroke is made by either side, cancel the stroke and play a ball, without penalty, as nearly as possible at the spot from which the original ball was last played (Rule 20-5) or he may play the ball as it lies. However, if the player elects not to cancel the stroke and the ball has come to rest in or on the opponent’s or his caddie’s clothes or equipment, the ball must through the green or in a hazard be dropped, or on the putting green be placed, as near as possible to the spot directly under the place where the ball came to rest in or on the article, but not nearer the hole.

Exception: Ball striking person attending or holding up flagstick or anything carried by him – see Rule 17-3b.

(Ball purposely deflected or stopped by opponent or caddie – see Rule 1-2)

19-4. By Fellow-Competitor, Caddie Or Equipment In Stroke Play
See Rule 19-1 regarding ball deflected by outside agency.

Exception:Ball striking person attending or holding up flagstick or anything carried by him – see Rule 17-3b.

19-5. By Another Ball
a. At Rest
If a player’s ball in motion after a stroke is deflected or stopped by a ball in play and at rest, the player must play his ball as it lies. In match play, there is no penalty. In stroke play, there is no penalty, unless both balls lay on the putting green prior to the stroke, in which case the player incurs a penalty of two strokes.

b. In Motion
If a player’s ball in motion after a stroke other than on the putting green is deflected or stopped by another ball in motion after a stroke, the player must play his ball as it lies, without penalty.

If a player’s ball in motion after a stroke on the putting green is deflected or stopped by another ball in motion after a stroke, the player’s stroke is canceled. The ball must be replaced and replayed, without penalty.

Note: Nothing in this Rule overrides the provisions of Rule 10-1 (Order of Play in Match Play) or Rule 16-1f (Making Stroke While Another Ball in Motion).

PENALTY FOR BREACH OF RULE:Match play – Loss of hole; Stroke play – Two strokes.