I belong to a large, geographically-distributed social organization. Everything the group does is the result of dedicated volunteers. Within this organization we have an award that is akin to a "lifetime achievement award" -- a prestigious, relatively rare award bestowed upon the members who have made a huge, positive difference within the organization.
Those who already have the award have a "community within the community". We discuss candidates for the award (we can recommend but do not make the decision), and we also talk about how to help people who are doing good work in this area (regardless of candidacy status), how we as a group can help the organization, and stuff like that. We're seen as a cohesive group by the broader membership; we're not just a collection of people who've received this award, but are also a group that works together to advance common goals. We communicate with each other via an email discussion list and occasional in-person meetings.
While discussions of broader topics aren't particularly confidential, the candidate list and discussions of candidates are. (This isn't like a university tenure-review board where everybody knows who's being discussed.) We've seen the damage that can arise when somebody who thought he was getting the award doesn't actually get it, and if deliberations about individual candidates aren't confidential, then (a) people will withhold critical comments and (b) leaked comments can cause upset. We need to discuss candidates, however, because not everybody knows every candidate personally (large, distributed group).
The problem is that there are a few members within this group who don't respect our confidentiality rules. In particular, they sometimes share things that were said in confidence with the candidates in question, when those candidates are their friends. (Or, occasionally, enemies -- we've seen this used to be hurtful too, unfortunately.) Sometimes they are deliberately violating our confidences; other times they think they are being careful about the source of the feedback but aren't.
We have already had numerous discussions, both in person and via email, about the harm this causes, but it continues. As a result, some people no longer participate in discussions, which hinders our ability to do our advisory job.
If we knew for certain who is doing this we would eject those people from the mailing list and meetings (at least temporarily), and those who bestowed the award could even revoke it (though this is very, very rare). But none of that happens because everybody denies it, evidence is circumstantial, and neither the community nor the leaders are ready to kick people out based only on rumor and circumstantial evidence. So we end up with a somewhat-toxic environment -- lots of suspicions, no actual proof -- but we don't know what to do about it.
This seems like a problem that would also be faced by personnel committees, HR groups, board of directors, and similar groups. What steps can we take to either persuade members to heed our confidentiality rules or identify them unambiguously so we can take action against them? The first is preferable.
Organization notes (in response to comments):
The (larger) organization is broken up into regions (kingdoms). Each region has rotating heads (royalty). Royalty can bestow this award (peerage) after consulting with those who already have it. (The existing peers don't, strictly speaking, have to agree, but usually royalty only bestow the award on people with strong support among the current members.)
Royalty can rescind a peerage; the latter is automatically reviewed by the larger organization's board of directors. Aside from this or matters specifically escalated to them, the board of directors almost never intervenes in the activities of the royalty. (Yes, there are checks and balances so the royalty can't, for example, spend the organization's savings.)
Organizational policies are silent on the subject of evicting a peer from the mailing list or meetings without taking the larger step of rescinding the award. I am, however, quite confident that we could achieve that, in the face of actual proof. Technically speaking, the meetings and mailing list aren't codified at all; they are an implementation detail for "must consult the members".