Rules of Golf
The USGA, in conjunction with The R&A in St. Andrews, Scotland, writes, interprets and maintains the Rules of Golf to guard the tradition and integrity of the game.The two organizations are joint authors and owners of The Rules of Golf and Decisions on the Rules of Golf.Through an agreement with The R&A, the Rules jurisdiction of the USGA includes only the United States, its possessions and Mexico.The latest version went into effect Jan. 1, 2012, with the next revision taking effect Jan. 1, 2016.
Golf Rule 15 - Wrong Ball; Substituted Ball
WRONG BALL - SUBSTITUTED BALL: A wrong ball is a ball that is not the players's own ball in play, a provisional ball played by the player, or a second ball put into play by the player in accordance with doubt as to procedure in stroke play.
TIP: If a ball is substituted it becomes the ball in play, even if the substitution was not permitted. For instance, a player marks and lifts his ball from the green. He replaces the ball with his lucky putting ball and plays. This substitution was not permitted and he is penalized two strokes in stroke play. The lucky putting ball now stays in play as the ball in play.