a) Ball moved at rest by opponent
Unless the rules provide otherwise, Rule 18-3b applies if the player's ball is touched or moved by an opponent, his caddie or his equipment, except when searching. The opponent incurs a penalty stroke in his hole play with the player concerned, but not in his hole play with the other opponent.
b) Ball accidentally deflected or stopped by an opponent
If a player's ball is inadvertently deflected or stopped by an opponent, his caddie or his equipment, this does not incur a penalty. In his hole play with that opponent, the player may, before another stroke is made by either party, cancel the stroke and play a ball as close as possible to the spot from which the original ball was last played (see Rule 20-5) or play the ball as it lies without penalty. In his hole game with the other opponent, the ball must be played as it lies.
Exception three-ball hole game: If a ball hits the person handling the flagstick, holding it up or anything carried by him - see Rule 17-3b.
(Ball deliberately deflected or stopped by opponent - see Rule 1-2.)
Status: 2018