The phrase "could well"appears two places in the laws (that I know of).
- Law 23: "Whenever...an offender could have be aware at the time of his irregularity that this could well damage the non-offending side...."
- "Law 83: "If the Director believes that a review of his decision on a point of fact or exercise of his discretionary power could well be in order, ....
The phrase is not given a technical definition, so it is worth knowing its natural meaning.
I believe this phrase is idiomatic. The definition is not in my dictionary, though it may be in others. More tellingly, the combinations "does well" or "is well" or "would well" or "should well" do not have the same meaning. For example, in "the irregularity did well damage the opponents', 'well' presumably picks up a dictionary definition, such as "to a considerable extent or degree".
However, 'might well' has the same meaning as could well. "Could/might very well" increases things, and "could/might well have" is also possible.
The Meaning of "Could Well"
Let's try this. The doctor says "He might well die tomorrow." That is different from saying "He might die tomorrow". The second sentence is, logically speaking, true about anyone. There might be Gricean principles that raise the probability -- why is the doctor saying that? But in "You should say you love him because he might die tomorrow", the phrase could mean just that he, like anyone else, might die tomorrow.
I think the doctor is saying that there is some reason why he might die tomorrow, such as a serious injury. This reason raises the probability above the level of just the background statistical probability. I think there is a second aspect to the meaning, which is that the probability has become worth considering.
When "could" is not synonymous with "might" but instead expresses ability, the word 'well' doesn't make sense. Example: "When I was young, I could well do 10 pullups."
The word 'well' also doesn't work very well when the background probability isn't raised for any reason. "The outcome of the coin toss could well be heads" or "The outcome of the die roll could well be a 1" or "John might well eat breakfast tomorrow."
So, to summarize, adding "well" after "could" or "might" says that there is some reason why the probability is increased beyond normal statistical levels, and it implies that this probability has become large enough that the possibility of the event has become worth considering.
My daughter and I are wondering about the name of a street. If I say "It could be Hospital Drive", I am uttering what is almost a truism -- as long as there are no other streets with that name around, the street could have any name. But if I say "It could well be Hospital Drive", then I am implying a reason for that name (we are near a hospital) and suggesting that name is worth considering.
Other examples. Young woman: "I went on a date with a guy last night. He might well be the one."
In Law 23
Law 23 should properly refer to expected value; "on average" (suggested by Richard Hill) is probably an easier phrase to understand with presumably the same meaning. It should also explicitly compare committing the irregularity and paying the expected rectifiation versus not committing the rectification. This removes an ambiguity in the laws.
"There should be a rectification when the player, at the time of the infraction, could have calculated that committing the irregularity and paying the proscribed penalty had a higher expected value than not committing the irregularity."
The old version of L23, which was actually found in Law 72B1, used the phrase "would be likely": "that the irregularity would be likely to damage the non-offending side". If "would be likely" refers to greater than 50%, this comes to the same thing as expected value when playing matchpoints, but it is not exactly the same thing at IMPs. The difference is probably unimportant, but to the extent they are different, expected value is the correct concept.
So the new law is different. In theory, if there was some irregularity that had insufficient penalty, then everyone would do it. It is not clear, at least to me, that the new L23 could be used. Fortunately, there is no such irregularity.
Instead, we do have that the probability of damage to the nonoffenders must be reasonable, or worth considering, but there is no reason it has to be greater than 50%. Instead, it just has to be worth considering. That makes a fuzzy line, but it doesn't seem to be too much of a problem. We were maybe going to have a fuzzy line anyway. It probably isn't in the right place, but that doesn't seem to be a serious issue.
In Law 83
This phrasing works very well in Law 83, where the director need only warn the players about their right to appeal when there is no reason, beyond normal background probability, that such an appeal could be in order.