There’s a phrase in the Rules of Golf that you will hear from time to time: ā€œknown or virtually certainā€. On the surface, it might sound a touch ambiguous, particularly when trying to apply it to any specific ruling in which the term comes into play.

For example, the landing area for your tee shot is over a hill so you can’t see it, but you know there’s a pond to the left of it. You hit your tee shot left of the fairway and upon reaching the landing area, you can’t find your ball. Can you assume your ball is in the pond and proceed under the rules for a penalty area? The answer is yes, if it is ā€œknown or virtually certainā€ your ball is in the pond. But how do you define that?

ā€œKnown or virtually certain,ā€ as it pertains to the rules in this instance, means that either there is conclusive evidence your ball is in the pond ā€“ such as someone from another group saw it go in ā€“ or there is at least a 95-percent chance, based on available evidence. A similar standard is used when applying the term throughout the rules book. According to the R&A and USGA, “known or virtually certain” means “more than just possible or probableā€.

Your job then in this and other rules instances when trying to apply the standard is to collect evidence to help you decide how to proceed. The rules provide some specifics in certain circumstances. For instance, when determining whether a ball moved or not, the R&A and USGA note that depending on the circumstances, reasonably available information may include, but is not limited to:

  • The effect of any actions taken near the ball (such as movement of loose impediments, practice swings, grounding club and taking a stance),
  • Time elapsed between such actions and the movement of the ball,
  • The lie of the ball before it moved (such as on a fairway, perched on longer grass, on a surface imperfection or on the putting green),
  • The conditions of the ground near the ball (such as the degree of slope or presence of surface irregularities, etc.), and
  • Wind speed and direction, rain and other weather conditions.

Keep in mind that when collecting evidence, you need to do it before the three-minute search time elapses (otherwise the ball by definition could be deemed lost). It has to be collected “with reasonable effort and without unreasonable delay”, the rules state.

Collecting evidence for a weekend round is a whole lot different than what the pros are accustomed to in a tour event. With cameras, marshals and spectators around, there always seems to be conclusive evidence of what transpired. Sam Burns was on camera last year at the Sanderson Farms Championship when his tee shot hit a power line running across the hole. It was clear from the footage that the ball was deflected by the line, satisfying the ā€œknown or virtually certainā€ criteria.

Getting back to the 95 percent chance aspect of the term: it could be that someone heard and saw a “splash” at that pond after you teed off and, in looking down into the water, you see a ball that looks like it has your markings but can’t be retrieved. You could make a case in this instance that it’s virtually certain your ball is in the penalty area. You can proceed under the options for relief from a penalty area, estimating where your ball last entered it (Rule 17.1d).

Another time when ā€œknown or virtually certainā€ might come into play is when you believe someone picked up your ball. Unfortunately, unless there are witnesses or you actually confront the person and he or she confesses, it would be difficult to say you are 95 percent sure it happened. Even worse, if you confront the person after a three-minute search period has elapsed, the ball is considered lost and you have to put another ball in play under the stroke-and-distance penalty (Rule 18.2b).

In any scenario where ā€œknown or virtually certainā€ applies, you can always ask the committee to make the determination. If you’re out on the golf course and that’s not practical, you can play two balls on that hole and await a decision by your course’s head pro or rules chairperson. But remember, playing two balls only applies to strokeplay. In matchplay, the decision by you and your opponent/s on whether something is virtually certain must take place on that hole as playing two balls is not permitted (Rule 20.1b).

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