A player's ball is resting against the flagstick. Without the player's authority, his opponent or a fellow-competitor removes the flagstick and the ball moves away from the hole. What is the ruling?
In match play, the opponent incurs a penalty stroke and the ball must be replaced against the flagstick - Rule 18-3b. In stroke play, the ball must be replaced against the flagstick without penalty to anyone - Rule 18-4. In either form of play, the player may then move or remove the flagstick as prescribed in Rule 17-4.