Rules
 

There was a situation today at the Open where Mickelson had an embedded ball off the fairway and took a penalty stroke after being refused relief. As I understand it, the USGA and the R&A rules are different for this condition.

I am reminded of the 1958 Masters that involved an embedded ball on 12. AP sought and was refused a free drop. He subsequently played a second ball and was ultimately permitted to record the score on it by the committee. The Masters is not a USGA event but at that time there was a local rule AP understood and took advantage of, ultimately winning for what was the first of four green jackets.

Anyone know more about this rule difference?

Just the rules of golf
 

This the rules of golf. Same ones for USGA and R&A:

25-2. Embedded Ball
A ball embedded in its own pitch-mark in the ground in any
closely-mown area through the green may be lifted, cleaned
and dropped, without penalty, as near as possible to the spot
where it lay but not nearer the hole. The ball when dropped
must first strike a part of the course through the green.
“Closely-mown area” means any area of the course, including
paths through the rough, cut to fairway height or less.

Sometimes professional tournements may have a different local rule for this circumstance.

I believe it was Clampett who made the comment about a difference. Maybe the US Tour does play under a Local Rule. A Google search for "Mickelson and embedded ball "produced several references to news articles. Here is one of them-

"It was an adventuresome second round which featured an interesting ruling on the second hole where Mickelson had to take a penalty stroke for relief from an embedded lie in a sand dune. That's different than the American rule allowing a drop from an embedded lie. Here, a free drop is granted only if a ball is embedded in a mown area.

The ball rolled forward after two drops and several more attempts to place the ball. Finally, when the ball was deemed to have been properly placed, Mickelson left the area to make his club selection. That's when the ball started rolling again to the fringe of the green and an official ruled the ball in play. Mickelson two-putted for bogey 5.

"Fifty-one weeks out of the year it includes the whole golf course and this week it's got to be just the closely mown areas," Mickelson said."

I think that’s a local rule on the US tour
 

I think that’s a local rule on the US tour.

Rules were not made to be broken.
 

It caused quite a controvesy a year or two ago when Ken Venturi authored "Getting Up and Down" and pretty much accused Palmer of violating the rules and Cliff Roberts giving Palmer preferencial treatment.

The rules of golf give relief for an embedded ball in closely mown areas.
The USGA for the PGA tour give relief for embedded balls in the rough as well as closely mown areas.(this has caused a lot of arguments at my own course).
Play the ball as it lies-you hit it there!:golf: