The USBGF Rules were ratified by the members in August 2017 and are used at all tournaments on the American Backgammon Tour (ABT) and many local clubs. It is safe to say that within the three pages of text comprising this new rule set, nothing has created more strong opinions and uncertainty than the two words “or checkers” contained within the Valid Rolls rule — the words that establish dice landing on top of checkers as valid.
According to ABT tournament directors, the vast majority of requests for die-on-checkers rulings made to date resulted from player uncertainty about what the rule actually said and how to apply it. In the first year that the die-on-checkers rule was implemented, only one ruling was categorized by the director as non-obvious for someone who fully understood the rule. By comparison, two rulings were made during the same period where assessing the validity of a die on the playing surface was described as a non-obvious call. Therefore, it is important that everyone is educated so that they understand this rule and can easily apply it over the board. Believe it or not, the uncertainty about valid rolls is not limited to dice on top of checkers, so we’ll look at the broader topic.
The scope of this article is limited to the implications of the one rule shown above — a roll has occurred, and you are called upon only to look at the dice and rule whether they are valid or not. After examining the various pictures and reading the explanations, you should be capable of correctly ruling on the validity of any dice roll you might encounter over the board.
The Valid Rolls rule starts with the necessary condition for a die to be valid. When the dice come to rest, they must both be either on the playing field or on the checkers. If both dice are so located, then the roll is usually valid (we’ll get to the exceptions later). If either die is not so located, then the entire roll is not valid. It is fine if one die is on the playing surface and the other is on the checkers.
Figure 1 shows a die on the playing field. The tip of the point it is on is peeling up. Figure 2 shows a die on a checker that has a finger dip. Figure 3 shows a die that is straddling two checkers; the checkers are of different heights.
These are all valid rolls. “But the dice are not flat,” you say? You are correct, but let’s look at the rule text. Is the die in the first picture on the playing field? Are the dice in the second and third pictures on checkers? Yes. So, they all meet the necessary condition for being valid. And as you will soon see, there is nothing else in the rule to invalidate them. Very simply: the word “flat” does not appear anywhere in the current rule. Being flat never matters when judging a roll’s validity. These are all imperfections in the horizontal plane of the playing surface or the horizontal plane of the checker-tops. What matters is that the die rests on one imperfect plane or the other. All three of these dice do.
Additionally, both dice must come to rest on the same side of the bar that they were rolled. This must be the roller’s right-hand side (unless a baffle box is in use). There is no provision in the Rules for asking to roll on the other side of the bar. There is less need now; the checkers no longer reduce the area available for the dice to land.
Figure 4 shows an invalid roll. One die has come to rest on top of the other. Even though the dice have come to rest within the playing area on the right side of the bar and are both flat, the top die does not meet the necessary conditions for validity because it is not on the playing surface and it is not on the checkers; it is on another die. Not only is flatness unnecessary for validity, it also doesn’t confer validity. Next, the Valid Rolls rule states three exceptions — conditions that make a die invalid even though it otherwise meets the above necessary conditions for validity.
What vertical surfaces exist near the playing surface and checkers? Primarily the bar and side rails of the board and bear-off tray that bound the four sides of the playing surface, but also the sides of the dice and checkers. There are no others. The tops of the checkers and the materials of the playing surface are considered horizontal surfaces no matter how their imperfections may cause them to deviate from a perfect plane. The checker’s top circumference edge is considered to be part of the checker’s top surface. What does it mean that a die is supported by a vertical surface? It means that the die is being held up and would fall if the vertical surface were suddenly erased from existence and no longer providing support. Merely touching a vertical surface therefore does not mean supporting, because the die is not being held up and would not fall in the absence of the surface it is touching.
Figures 5 through 8 all show invalid rolls because a die is supported by either the bar, a side rail, or the side of another die, all of which are vertical surfaces. It doesn’t matter whether the die is on the playing surface or on the checkers, or if the die is rising or falling when supported by the vertical surface: if the vertical surface were not there, the die would drop.
To review the complete USBGF Tournament Rules, Ruling Guide, and Tournament Options, please visit usbgf.org/tournament-rules
Valid Roll & Test for Vertical Support
Figure 9 shows a valid roll. The die is not being supported by the side rail; it is merely touching it. It is almost always obvious whether a die has vertical support or is simply touching the vertical surface. But how can we be sure in those rare instances where it is not obvious? We can gently slide the checker(s) supporting the die away from the vertical surface in question and observe whether the die drops by any amount or remains fixed in place on top of the checker(s). In Figure 10 we have slid the checker and the die did not drop, thus confirming that it had no vertical support. Of course, if such a dispute were to occur during a match, the players should not physically alter the evidence; the director should be called if the players cannot agree. Generally, unless there is clear evidence of vertical support, the ruling should be that no vertical support exists.
Sometimes a die will land on the playing surface perfectly balanced on its corner. Usually, it will tip over. However, if two seconds pass and it remains balanced, it is considered to have come to rest. It is best to say “invalid” or “cocked” when this occurs to avoid any dispute in case the die later tips over. A player must never intentionally disturb the equipment to cause a die to fall (or otherwise influence its validity).
Figure 11 shows an invalid roll. This die has come to rest balanced on its corner. While you may never see a die come to rest similarly balanced on its edge, or so balanced on top of a checker, those outcomes are possible and would also render the roll invalid.
Sometimes a die is on but falling off the checkers, without support by any vertical surface. The intent here is that if a die is on the checkers, but any part of the die descends low enough to be below the top surface of all of the checkers that are supporting it, then the roll is invalid. A die that is only on a single checker and touching nothing else is never invalidated by this condition; if the die hasn’t fallen off the checker, then it is considered to be entirely on and above the top surface no matter how tilted it might be.
Figures 12 and 13 both show an invalid roll. Although each die meets the necessary condition of being on the checkers, they are falling into the gap between the checkers, with part of each die clearly descending below the top surfaces of all checkers that support it.
Figure 14 shows an invalid roll. When the rule says that a die must come to rest “on the playing surface or checkers,” the word “or” is ambiguous because it isn’t clear whether a die is valid or invalid if it is on both surfaces at the same time. However, that ambiguity is moot. The die is rendered invalid because it is clearly descending below the top surface of all checkers on which it rests.
Figure 15 shows a valid roll. Because the checkers are of different heights, part of the die is descending below the top surface of one of the checkers, but it remains fully above the top surface of the second checker. Since it is not descending below the top surface of all checkers, this test does not invalidate the die.
While new rules always take some getting used to, you will find the game more enjoyable if you fully understand the rules and know how to apply them over the board. At first, using the dice-on-checkers rule might give you a few deer-in-headlights moments. But if you are like most people, with some time to adjust to the change you will like being able to play when your dice land validly on checkers instead of having to reroll them. And after this lesson you will be an expert, able to correctly rule on the validity of any dice roll!