The concept of “virtual certainty” is among the more misunderstood elements in the Rules of Golf. It serves as the standard for determining what happened to a player’s ball – for example, whether it came to rest in a penalty area, whether it moved, or what caused it to move.
When a ball isn’t found, determining if virtual certainty exists is the key factor that must be met before a player may proceed under the applicable Rule rather than treating the ball as lost. That distinction matters, because the relief options available from a penalty area or obstruction are almost always better than those when proceeding under stroke and distance.
Under the Rules, virtual certainty means that, although a very small degree of doubt may remain, all reasonably available information shows it is at least 95 percent likely that the event in question occurred. When we say “all reasonably available information,” that includes everything the player knows, as well as any information they can obtain with reasonable effort and without undue delay. This standard is significantly higher than the threshold of “more likely than not.”
A helpful way to think about this standard is: If this shot were played 20 times, would the ball finish in the Penalty Area or Obstruction 19 or more times out of 20?
The surrounding conditions play a big role. Heavy rough or trees can make for a very different judgment than closely mown fairway or short rough in the area. A good question to ask yourself is, “Is there anywhere else the ball could reasonably be?”
During the 2025 Ryder Cup at New York’s Bethpage Black, I was the match referee for the first Saturday afternoon Four-ball match between Europeans Rory McIlroy and Shane Lowry and the U.S.’s Justin Thomas and Cameron Young. When the match reached the 16th hole the European side was ahead 1-up. Thomas (pictured) pulled his tee shot left toward a large two-story hospitality structure defined as a Temporary Immovable Object (TIO). As we walked toward the fairway, it became apparent that locating the ball – or determining with virtual certainty that it was in the TIO – would be crucial in applying the Rules.
Spectators between the fairway and the TIO were already searching the area. I moved past the crowd to speak with the TV cameraman who had tracked the tee shot. He confirmed that the ball had flown into the upper level of the TIO and had not bounced out. That information, combined with the well-searched and trampled-down grass between the fairway and the TIO, was sufficient to establish virtual certainty that the ball was in the TIO.
PGA Rules Committee Member Jon Drago was serving as a forward observer for the match. By the time I returned to the area where we believed the ball had entered the TIO, Jon radioed that the ball had been located on the second level of the TIO, allowing Thomas to proceed with taking relief based on the location of the ball. Incidentally, Jon also did an exceptional job on the previous hole locating McIlroy’s ball after it entered a TIO on the left side of the 15th hole. The match observers did a great job of locating these errant shots and making sure we didn’t have to make a ruling based on the virtual certainty concept.
In both instances, the balls were ultimately found. Had they not been, determining whether virtual certainty existed that the balls were in the TIO would have been critical to applying the correct Rule and determining the players’ available options.
Mike Raby, PGA, is Vice Chairman of the PGA of America Rules Committee and the PGA of America Director of Golf for BREC Golf Courses in Baton Rouge, Louisiana.
