Ball in motion
The R&A / USGA · 2023Accidental contact and deliberate interference have different consequences.
Accidental contact
A moving ball accidentally hitting a person or outside influence normally brings no penalty and is played where it rests. In stroke play, however, hitting another ball at rest on the green costs 2 penalty strokes if both balls were on the green before the stroke. Special procedures apply if the ball rests on a person, animal or moving outside influence, and to certain collisions after a stroke from the green.
Replay and deliberate interference
A putt must be replayed after hitting a person on the green other than the player or flagstick attendant, certain movable obstructions, or an animal other than a loose impediment. Exceptions include the striking club, ball-marker, resting ball and flagstick. Deliberately deflecting or stopping a moving ball normally brings the general penalty. After a stroke off the green, relief uses the estimated finishing spot; after a putt, replay the stroke.
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