All defined terms are in italics and are listed alphabetically in the Definitions section – see pages 2235.
A player in doubt as to the conformity of a ball should consult the USGA.
A manufacturer should submit to the USGA samples of a ball to be manufactured for a ruling as to whether the ball conforms with the Rules. The samples become the property of the USGA for reference purposes. If a manufacturer fails to submit samples or, having submitted samples, fails to await a ruling before manufacturing and/or marketing the ball, the manufacturer assumes the risk of a ruling that the ball does not conform with the Rules.
The ball the player plays must conform to the requirements specified in Appendix III.
Note: The Committee may require, in the conditions of a competition (Rule 33-1), that the ball the player plays must be named on the current List of Conforming Golf Balls issued by the USGA.
5-2. Foreign Material
The ball the player plays must not have foreign material applied to it for the purpose of changing its playing characteristics.
PENALTY FOR BREACH OF RULE 5-1 or 5-2:
5-3. Ball Unfit for Play
A ball is unfit for play if it is visibly cut, cracked or out of shape. A ball is not unfit for play solely because mud or other materials adhere to it, its surface is scratched or scraped or its paint is damaged or discolored.
If a player has reason to believe his ball has become unfit for play during play of the hole being played, he may lift the ball, without penalty, to determine whether it is unfit.
Before lifting the ball, the player must announce his intention to his opponent in match play or his marker or a fellow-competitor in stroke play and mark the position of the ball. He may then lift and examine it, provided that he gives his opponent, marker or fellow-competitor an opportunity to examine the ball and observe the lifting and replacement. The ball must not be cleaned when lifted under Rule 5-3.
If the player fails to comply with all or any part of this procedure, or if he lifts the ball without having reason to believe that it has become unfit for play during play of the hole being played, he incurs a penalty of one stroke.
If it is determined that the ball has become unfit for play during play of the hole being played, the player may substitute another ball, placing it on the spot where the original ball lay. Otherwise, the original ball must be replaced. If a player substitutes a ball when not permitted and makes a stroke at the wrongly substituted ball, he incurs the general penalty for a breach of Rule 5-3, but there is no additional penalty under this Rule or Rule 15-2.
If a ball breaks into pieces as a result of a stroke, the stroke is canceled and the player must play a ball, without penalty, as nearly as possible at the spot from which the original ball was played (see Rule 20-5).
*PENALTY FOR BREACH OF RULE 5-3:
Match play – Loss of hole; Stroke play – Two strokes.
*If a player incurs the general penalty for a breach of Rule 5-3, there is no additional penalty under this Rule.
Note 1: If the opponent, marker or fellow-competitor wishes to dispute a claim of unfitness, he must do so before the player plays another ball.
Note 2: If the original lie of a ball to be placed or replaced has been altered, see Rule 20-3b.
(Cleaning ball lifted from putting green or under any other Rule – see Rule 21)