The Chatham House rule is an organizing principle for the international think thank Chatham House. It states1:
When a meeting, or part thereof, is held under the Chatham House Rule, participants are free to use the information received, but neither the identity nor the affiliation of the speaker(s), nor that of any other participant, may be revealed.
The goal is to allow participants to have open and frank conversation.
References
1.
Chatham House Rule. Chatham house international affairs think tank Website at https://www.chathamhouse.org/about-us/chatham-house-rule.