What happens if you accidentally move the ball when taking a practice swing on the course?
Well, you have not actually taken a stroke—the forward movement of the club with the intentions of striking at and moving the ball. Therefore, the penalty is one stroke for moving the ball and the ball must be replaced.
However, if you did the same thing on the teeing ground, the ball was not actually in play and therefore there is no penalty. You just tee it up again.
In a tournament that I played in Abilene, TX way back when I was in my 20s and the sports editor of the local newspaper, a player’s putt stopped on the lip of the hole. In disgust, he knocked the ball off the green with the back of his putter. One of the other players told him he had to play from there. However, being up on the rules, I realized he was wrong and informed the other player that he had not actually made a stroke. I told him to replace the ball on the lip and add a penalty stroke. The golf professional confirmed my view on the rules. The angry golfer ended up losing by a stroke because of this fit on anger.

In one of the Dallas District Golf Association events two years ago, I had to remind a fellow competitor that he incurred a penalty stroke when he reached for and pulled back the ball after missing a short putt for par,. He had to settle for a double bogey instead. Yes, he also lost a prize by the margin of the penalty stroke, but remains one of my best friends today—at least I think so.
There is no penalty involved if a player accidentally causes his ball to move in the following circumstances:
*In searching for a ball in a hazard covered by loose impediments, for a ball in an obstruction or abnormal ground condition or for a ball believed to be in water in a water hazard.
*In repairing a hole plug or ball mark, in measuring, in lifting, placing or replacing a ball under a rule or in removing movable obstructions or loose impediments on the putting green.
James McAffee is a former editor of Golf Digest Magazine who currently writes about the rules of golf and travels for www.examiner.com