Rule 5-1 provides that the ball that a player uses must conform to the Rules and that the use of a ball which does not conform to the Rules will result in disqualification. However, the player would have to play a stroke with a non-conforming ball in order for the disqualification penalty to apply (see also Decision 5-1/3 in “Decisions on the Rules of Golf”).
The List of Conforming Golf Balls
Manufacturers may submit balls to the United States Golf Association and The R&A for testing. Twenty-four samples of each ball type (model) must be submitted to obtain a conformance ruling. If the samples conform to the Rules, they are entered onto the List of Conforming Golf Balls, which is updated on a monthly basis. The current list can be found on the USGA’s Web site at www.usga.org. Full details of the golf ball submission procedure can be obtained from the USGA.
Ball types remain on the List for one year. However, random tests are carried out by the USGA and The R&A on selected balls to ensure that the ball characteristics remain the same. If a conformance issue is identified during random testing, the ball may be removed from the List.
Normally, only the Committees in charge of competitions involving expert players (at the state, regional and national level for amateurs, or at professional events) introduce a Condition of Competition requiring a player to use a ball included on the List of Conforming Golf Balls, the penalty for breach of the Condition being disqualification. However, if this Condition is not in place, it is assumed that a ball used by a player conforms unless there is strong evidence to the contrary (e.g., a player used a 1.62 inch diameter golf ball).
Foreign Material (Rule 5-2)
As with the club, the most important question to ask if confronted with a ball which has had something applied to it by the player is “why did the player apply it?” If the purpose of the application is to influence the movement of the ball, it would be prohibited.
Markings applied to the ball by the player (e.g., using a felt-tip pen) are not contrary to this Rule. Rules 6 5 and 12 2 encourage the player to put an identification mark on his ball to help ensure that he plays his own ball throughout the round. There are no regulations to limit what or how many markings can be applied to the ball by the player, provided its original markings can be discerned.