Now i've seen many golfers and played with many that have this unwritten rule that movement of a ball less that a quarter revolution is not considered a violation during address of the ball.

I would think that Tour course have think roughs that keep the ball sitting up could lead to a lot of problems for golfers that address the ball normally (club behind the ball). But in alot of cases the ball would move down if you touch the surrounding areas of the ball. This is a penalty, no? I usually take a bunker mentality and not touch any grass when I'm over the ball for the fear of it moving but I've seen lots of pros that set the club behind the ball in the thick stuff. Is the grass different that would prevent ball movement? or is there no penalty for this?

If the ball *moves* from its place of rest, after address...that counts as a stroke,
as the player is deemed to have moved the ball. It does not matter how much
or little it moves (from its place of rest). If a ball merely *oscillates* ....
there is no stroke (or penalty).

Your approach with questionable lies, is, I believe, the best (safest).
My guess is that the pros, when they ground their clubs in the rough, is no more than
their experience in reading the lie, that tells them it is safe to ground the club
without moving the ball. If they guess wrong, and it has happened,
they too, add 1 to the score.

Rule 18-2 states:

b. Ball Moving After Address

If a player's ball in playmoves after he has addressed it (other than as a result of a stroke), the player is deemed to have moved the ball and incurs a penalty of one stroke. The ball must be replaced, unless the movement of the ball occurs after the player has begun the stroke or the backward movement of the club for the stroke and the stroke is made.


Decisions on this ruling state:

18/1 Ball Moves Vertically Downward

Q. A ball lying in long grass slips vertically downward. Or a ball is accidentally stepped on and pressed down, say a quarter of an inch, in the grass or into the ground. In each case, has the ball moved?

A. Yes, unless the ball returns to its original position. The direction of movement is immaterial.

18/2 Ball Oscillates During Address

Q. In addressing the ball, a player accidentally causes the ball to oscillate, but it returns to its original position. Has the ball "moved"?

A. No.

If the ball moves after address, it does not count as a stroke.
The player must replace the ball and add a penalty stroke to the score (Rule 18-2b)

So what is the ruling if the ball begins to move as the player is part way through the backswing, and then he continues to swing and hits the ball? (this has happened to me). It is easy to happen on something like pine straw where the foot movement can end up pulling something a foot or more away.

If the ball moves after you swing your club back then you are ok according to this section of the rule "... unless the movement of the ball occurs after the player has begun the stroke or the backward movement of the club for the stroke and the stroke is made."

So you are saying that if the ball moves as I am part way through my swing, I must stop and replace the ball, at no penalty?

I read it as you don't stop your swing to replace the ball but you do add a penalty stroke.

The way I read that is that you are not required to stop your swing and replace the ball, but you still incur the 1 stroke penalty for causing the ball to move.

No to all those. I had a conversation with a rules official on this very scenerio last year.

If you have started your swing, and the ball moves, DON'T STOP. You will only incur a penalty if stop. If you finish your swing, then the movement of the ball is considered to have been moved by the act of taking the stroke.

Except on the tee box where if the wind or even YOU knock the ball off the tee without obvious hitting intention, you're not penalized and you can simply re-tee...even if you were at address.

(Baxpin you are correct also - Especially when under a tree if you take a swing and clip a branch and then halt your swing because it freaked you out, it's a stroke.)

So, what you are saying is that if I start my backswing, and the ball rolls an inch back, as long as I finish my swing, I do not incur a penalty? I dont believe that for a second, and the rule clearly states otherwise.

"If a player's ball in play moves after he has addressed it (other than as a result of a stroke), the player is deemed to have moved the ball and incurs a penalty of one stroke. The ball must be replaced, unless the movement of the ball occurs after the player has begun the stroke or the backward movement of the club for the stroke and the stroke is made."

Per the USGA, the definition of a 'stroke" is:

Stroke
A "stroke" is the forward movement of the club made with the intention of striking at and moving the ball, but if a player checks his downswing voluntarily before the clubhead reaches the ball he has not made a stroke.

If you initiate your backswing, and the ball moves, it is a one stroke penalty, regardless if you stop or continue and hit the ball. The rule states that the ball must be replaced unless the movement occurs after you have initiated your backswing or stroke and the stroke is made, but it does not say that you do not incur a penalty.

Directly from the USGA Site:

Rule 14-5

Ball Moves after Address, Player Strikes Moving Ball

Q. After the player has addressed his ball and begun the backward movement of the club for his stroke, the player’s ball begins to move. The player continues his stroke and strikes the ball while it is still moving. Is there a penalty?

A. Yes. The player incurs a one stroke penalty under Rule 18-2b for his ball in play moving after he addressed it. However, there is no penalty for playing a moving ball in this case as the ball started to move after the player had begun his swing.

That is exactly what I said. There is a one stroke penalty for the players ball moving after he addressed it. That decision is stating that there is not an additional penalty for hitting the moving ball.

You have misunderstood the RO or the RO has misunderstood the Rule.

Ok, I had to call an official for a ruling, and I got some bad information. You get a penalty for the ball moving, but no penalty for hitting a moving ball or a penalty for not replacing it to it's original position. Sorry for the confusion.