Your ball is on the putting green and you’ve lifted it, cleaned it and replaced it. After reading your putt, you are ready to play. You place your club on the ground immediately behind the ball. But before you hit the ball, it rocks and falls forward, moving ⅛ of an inch. What is the ruling? Rule 18-2b – Ball at Rest Moved – After Address states that once you have addressed your ball, which you did when you grounded the club immediately behind the ball, you are deemed to have caused any movement that occurs. In 2012, an Exception was added to this Rule which states that if it is known or virtually certain that some other agency caused your ball to move, you are not penalized for the movement and must proceed appropriately under the Rules (see also Decision 18-2b/11 – Ball Moved by Another Agency After Address). This Exception was added to cover situations such as a ball that is moved by wind on a blustery day. However, what if it isn’t windy at all? Can you claim that gravity caused your ball to move? The answer to this question is found in the new Decision 18-2b/1 – Ball Moves After Address; Movement May Have Been Due to the Effect of Gravity. The Decision states, “The effects of gravity do not satisfy the Exception to Rule 18-2b. The Exception only applies when it is known or virtually certain that the player did not cause his ball to move. In order to meet this standard, it must be known or virtually certain that some other observable factor (e.g., wind, water or an outside agency) caused the ball to move. Otherwise, the player is deemed to have caused the movement and Rule 18-2b applies.” Since gravity is not considered to be an “observable” factor, the Exception to Rule 18-2b cannot apply. Therefore, when your ball moves after address and there is no observable outside factor involved, you are penalized one stroke and must replace the ball. Remember, when your ball is teetering on the edge of a small bump or a severe slope in the green, be very careful or consider putting without grounding your golf club. The USGA will provide up to two Rules of Golf books for a minimal shipping-and-handling charge. Contact the USGA Order Department at 1-800-336-4446, Monday through Friday, 9 a.m. to 5 p.m. (ET) or go to the USGA Shop on usga.org.