2019 Rule: The prohibition of touching the line of play on the putting green will be eliminated:
There will no longer be a penalty for merely touching the line of play on the putting green (the term “line of play” will apply everywhere on the course including the putting green, and the term “line of putt” will no longer be used).
But the player will still be subject to the prohibition on improving his or her line of play on the putting green (see Rule 8.1a, as limited by 8.1b).
Reasons for Change:
No advantage is gained if a player or his or her caddie merely touches the surface of the putting green on the line where the ball will be played.
Over time, the prohibition on touching the line of putt has become subject to many exceptions:
Current Rule 16-1a lists seven different situations in which a player is allowed to touch the line of putt.
The current prohibition is difficult to administer and penalties are not often applied; and those penalties that are applied may be perceived as serving little or no purpose, such as when a caddie accidentally touches the line of putt with the flagstick.