Rule 18. Ball at rest Moved

Definitions

A ball is deemed to have 'moved' if it leaves its postition and comes to rest in any other place.

An 'outside agency' is any agency not part of the match or, in stroke play, not part of the competitor's side, and includes a referee, a marker, an observer or a forecaddie. Neither wind nor water is an outside agency.

Equipment is anything used, worn or carried by or for the player excep any ball he has played at the hole being played and any small object, such as a coin or a tee, when used to mark the position of a ball or the extent of an area in which a ball is to be dropped. Equipment includes a golf cart, whether or not motorised. If such a cart is shared by two or more players, the cart and everything in it are deemed to be the equipment of the player whose ball is involved except that, when the cart is being moved by one of the players sharing it, the cart and everything in it are deemed to be that player's equipment.

Note:

A ball played at the hole being played is equipment when it has been lifted and not put back into play.

A player has 'addressed the ball' when he has taken his stance and has also grounded his club, except that in a hazard a player has addressed the ball when he has taken his stance.

Taking the 'stance' consists in a player placing his feet in position for and preparatory to making a stroke.

18-1. By Outside Agency

If a ball at rest is moved by an outside agency, the player shall incur no penalty and the ball shall be replaced before the player plays another stroke.

(Player's ball at rest moved by another ball - see Rule 18-5)

18-2. By Player, Partner, Caddie or Equipment

a. General

When a player's ball is in play, if:

(i) the player, his partner or either of their caddies lifts or moves it, touches it purposely (except with a club in the act of addressing it) or causes it to move except as permitted by a Rule, or

(ii) equipment of the player or his partner causes the ball to move, the player shall incur a penalty stroke. The ball shall be replaced unless the movement of the ball occurs after the player has begun his swing and he does not discontinue his swing.

Under the Rules no penalty is incurred if a player accidentally causes his ball to move in the following circumstances:

In measuring to determine which ball farther from hole-Rule 10-4

In searching for covered ball in hazard or for ball in casual water, ground under repair, etc.-Rule 12-1In the process of repairing hole plug or ball mark-Rule 16-1c 

In the process of removing loose impediment on putting green - Rule 18-2cIn the process of lifting ball under a Rule - Rule 20-1

In the process of placing or replacing ball under a Rule 20-3 

In complying with Rule 22 relating to lifting ball interfering with or assisting playIn removal of movable obstruction - Rule 24-1.

b. Ball Moving After Address

If a player's ball in play moves after he has addressed it (other than as a result of a stroke), the player shall be deemed to have moved the ball and shall incur a penalty stroke. The player shall replace the ball unless the movement of the ball occurs after he has begun his swing and he does not discontinue has swing.

c. Ball Moving After Loose Impediment Touched

Through the green, if the ball moves after any loose impediment lying within a club-length of it has been touched by the player, his partner or either of their caddies and before the player has addressed it, the player shall be deemed to have moved the ball and shall incur a penalty stroke. The player shall replace the ball unless the movement of the ball occurs after he has begun his swing and he does not discontinue his swing.

On the putting green, if the bal or the ball-marker moves in the process of removing any loose impediment, the ball or the ball-marker shall be replaced. There is no penalty provided the movement of the ball or the ball-marker is directly attributable to the removal of the loose impediment. Otherwise, the player shall incur a penalty stroke under Rule 18-2a or 20-1.                                                             

18-3. By Opponent, Caddie or Equipment in Match Play

a. During Search

If, during search for a player's ball, it is moved by an opponent, his caddie or his equipment, no penalty is incurred and the player shall replace the ball.

b. Other Than During Search

If, other than during search for a ball, the ball is touched or moved by an opponent, his caddie or his equipment, except as otherwise provided in the Rules, the opponent shall incur a penalty stroke. The player shall replace the ball.

(Ball moved in measuring to determine which ball farther from the hole - see Rule 10-4.)

(Playing a wrong ball - see Rule 15-2.)

(Ball moved in complying with Rule 22 relating to lifting ball interfering with or assisting play.) 

18-4. By Fellow-Competitor, Caddie or Equipment is Stroke Play

If a competitor's ball is moved by a fellow-competitor, his caddie or his equipment, no penalty is incurred. The competitor shall replace his ball.

(Playing a wrong ball - see Rule 15-3.)

18-5 By Another Ball

If a ball in play and at rest is moved by another ball in motion after a stroke, the moved ball shall be replaced.

PENALTY FOR BREACH OF RULE:

Match play - Loss of hole; Stroke play - Two strokes.

If a player who is required to replace a ball fails to do so, he shall incur the general penalty for breach of Rule 18 but no additional penalty under Rule 18 shall be applied.

Note 1:

If a ball to be replaced under this Rule is not immediately recoverable, another ball may be substituted.

Note 2:

If it is impossible to determine the spot on which a ball is to be placed, see Rule 20-3c