In a natural languate, such as English, words (and hence phrases) are defined by the best example of the word. The dividing line between what counts as a instance of a word and what does not count as an instance of a word is never made clear.
For example, everyone has about the same definition of "furniture", and we all agree that chairs are furniture and spoons are not. But it is probably not obvious to you whether a piano, mirror, or spittoon is furniture, and a vote of native speakers is very unlikely to yield consensus.
That makes it very difficult to apply rules. If someone gave you money with the rule it had to be spent on furniture, it would be obvious that you could buy chairs and not buy spoons, but could you buy a piano? The rule would be vague and difficult to apply.
Vagueness in the LawsThe same problem occurs for words and phrases in the laws. For example, a player asks if the contract is 5H by East. The answer is yes. She faces an opening lead and is told that she led out of turn. The contract is 5H by West. I am called to the table. The Law is that "A lead out of turn may be retracted without penalty if the leader was mistakenly informed by an opponent that it was his turn to lead." Did the defenders ask whose lead it was? Did declarer answer incorrectly? I mean, declarer providing wrong information, leading to this person making the wrong lead. Is she protected by the Laws?
You might think the answer is obvious, but I can probably find two people who think the opposing answers are obvious. To me, this is just a situation where the answer is not clear. (I decided that the players are not obligated to remember who is East and who is West. Also, they might have thought the important part of the question was the contract and not seen the question as a request to identify the opening leader.)
So the law is vague. But it has to be -- it cannot address every possible question a player could ask about the lead.
Example 2Declarer cannot change a designation of a play from dummy (unless it was inadvertent). Obviously, a player can change his intended call with "Play the - I changed my mind, play the ten." Can the player change his mind with "Play the q-ten"? Can the player change his mind with "Play the queen-ten" Can the player change his mind with "Play the queen of - ten of hearts"?
The Laws do not say. Again, there is no obviously right answer. And if you think there is...
The Dutch bridge league says that a call cannot be changed once it is started. So "qu-ten" would not be an allowable change. I have opinions from Rick (presumably Rick Beye) at the ACBL and David Stevenson, Senior Consultant Director for the English Bridge Union. They both allow the qu-ten change, and they both disallow the queen-ten change, but Rick does not allow queen of-ten of hearts change and David Stephenson does.
It turns out that the laws are much clearer about when a card is played (and cannot be retracted). For example, if one defender could see another defender's card, it is considered played. But what if the other defender could only see the color? What if the defender only saw the white part of the card? And so on. No matter what, you can always find things that are on the boundary between categories and hence become ambiguous.
What to Do?In the face of serious vagueness, authorities will ususually make a supplemental ruling. For example, the ACBL Rules Commission made an effort to define "inadvertency". However, these rulings are not easy to access. (This particular ruling is in the ACBL's Duplicate Decisions).
If you notice a particular vagueness in advance, you can try to consult authorities. But it is unlikely you will notice this in advance. Also, the mere opinion of an authority is not very official. If the directors have sorted it out themselves and all make the same ruling, a new director would probably want to make the same ruling, but that information is not easy to find.
What if you are on your own? Good judgment is always appropriate. I tried to think about whether asking about the contract was the same as asking about opening leader. You can try to think about when you feel a call has been completed.
But that will not change the need for a decision -- the logic described above means that not only can we find a situation where approximately half of the people vote one way and the other half vote the other, we can also find a situation for any director such that the director is almost completely undecided which choice is correct. So just make your decision, and don't worry if the decision seems close.
Bottom Line: A director must make decisions to resolve vagueness in the laws.