USGA Rules and Decisions
14/1.5 Intent to Strike Ball Ceases During Downswing; Club Not Stopped But Path of Clubhead Altered to Avoid Striking Ball
Q. A player begins his downswing with the intention of striking the ball but decides during the downswing not to strike the ball. The player is unable to stop the club before it reaches the ball, but he is able to swing intentionally over the top of the ball. Is the player deemed to have made a stroke?
A. No. The player is considered to have checked his downswing voluntarily by altering the path of his downswing and missing the ball even though the swing carried the clubhead beyond the ball.
If the player had not successfully checked his downswing (i.e., he had struck the ball), he is considered to have made a stroke.
Any doubt regarding the player's intent must be resolved against the player.