The Crawford rule

Almost all offline backgammon tournaments have something called the Crawford rule. The Crawford rule is optional at most online backgammon sites, but it usually is in effect. So just what is the Crawford rule and why is it so often used?

The Crawford rule is quickly explained. It states, that if in a match either player comes within one point of winning the match, the next game is played without a doubling cube. Therefore, if a player wins a game to get a 8-6 lead in a nine point match, then the next game is played without the doubling cube. If the match becomes indecisive then the doubling cube is back in the following game again.

Why use the rule?

The Crawford may seem quite quite odd at first glance, but it makes ample sense if inspected more carefully. The reasoning behind the rule is, that without the rule backgammon matches would see quite a bit of bizarre doubling cube action.

Consider the following scenarios:
Score is 8-6 in a nine point match and the next game begins. Without the Crawford rule the trailing player might just as well double on his first turn, as he has nothing to lose.

Score is 5-6 in a nine point match. The player with 5 points doubles. Without the Crawford rule the player in the lead could accept the double without hesitation, no matter how poor his position was (barring a gammon threat). Why? Because after his loss the score would be 7-6 and in the beginning of the next game he could just double blindly. This way the player who improved his position from 5-6 to 7-6 didn’t actually gain anything at all!

So the rule makes sense, but why not simplify it? Wouldn’t it work, if doubling was altogether banned after one player is just one point away of winning a match? Well, no it wouldn’t. Consider a score like 8-4 in a nine point match. If doubling was banned altogether for the rest of the match, it would make it nearly impossible for the trailing player to win the match, as he would need to win five times in a row. With the Crawford rule it is still difficult to make a comeback, but at least it is possible.

Final thoughts

It is highly recommended that you choose to use the Crawford rule if you play backgammon at a site where the rule is optional (like Gammon Empire or Play65). It is not by any means a perfect rule, but it is a good compromise: The Crawford rule makes it valuable to get into close proximity of winning a match, but at the same time the it leaves the trailing player a fighting chance.