In the light of the Master's statement that the deliberations of Assemblies must be secret and confidential, it is not possible to have a non-Assembly member in the National Spiritual Assembly meeting. You must always remember that in matters of principle, there can be not deviation; ... Highly personal subjects, damaging to the honor and happiness of others, are often taken up by National Assemblies, and the danger that confidence will be betrayed is already great enough with the 9 chosen representatives of the whole community, let alone introducing non-Assembly members. You will just have to make your minutes a little more compact and sacrifice, if necessary, a certain amount of efficiency in order to follow this very important principle.

Shoghi Effendi, Lights of Guidance, p. 45-46

Regarding the matter ... and the inharmony that seems to exist among certain of the friends ... When Bahá’ís permit the dark forces of the world to enter into their own relationships within the Faith they gravely jeopardize its progress; it is the paramount duty of the believers, the Local Assemblies, and particularly the N.S.A. to foster harmony, understanding and love amongst the friends. All should be ready and willing to set aside every personal sense of grievance -- justified or unjustified -- for the good of the Cause, because the people will never embrace it until they see in its Community life mirrored what is so conspicuously lacking in the world; love and unity.

Shoghi Effendi, Lights of Guidance, p. 165-166

The demands of the Cause transcend those of the individual, and should therefore be given precedence. But these two phases of Bahá’í social life, though not of equal importance, are by no means contradictory. Both of them are essential, and should be fostered, but each according to its own degree of importance. It is the responsibility of Bahá’í Assemblies to decide when individual interests should be subordinated to those affecting the collective welfare of the community. But, as already stated, the interest of the individual should always be safeguarded within certain limits, and provided they do not seriously affect the welfare of the group as a whole.

Shoghi Effendi, Lights of Guidance, p. 121

With regard to your question as to the advisability of disclosing to an individual believer the contents of the National Spiritual Assembly's correspondence: The Guardian thinks that although this cannot be considered as constituting an obligation which a believer can impose upon the national body, yet it would seem highly advisable that the National Spiritual Assembly should give a sympathetic consideration to any such request made to it by a believer. This, he feels, would avoid giving the impression that the Assembly is working in an atmosphere of complete secrecy, and that it is motivated by dictatorial motives. The final decision in such matters, however, is entirely left to the discretion of the National Spiritual Assembly. The basic principle that should always be remembered is that the National Spiritual Assembly cannot be required to reveal to any outsider all the details concerning its work. It may choose to do so if it wishes, but nobody has the right to enforce upon it any such action. This is, of course, the purely legal side of the question. But a purely legalistic attitude in matters affecting the Cause, particularly now that the Faith is still in a state of infancy, is not only inadequate but fraught with unforeseen dangers and difficulties. The individuals and Assemblies must learn to co-operate and to co-operate intelligently, if they desire to adequately discharge their duties and obligations towards the Faith. And no such co-operation is possible without mutual confidence and trust.

Shoghi Effendi, The Compilation of Compilations vol II, p. 91-92

Any believer meeting with the Local Spiritual Assembly, while he may be entirely willing to share freely and frankly all his views, can certainly refuse to have his discussion with the Assembly recorded on tape. Obviously lying and backbiting among the friends are prohibited most categorically in the Faith, but when a friend is reporting to the Assembly on a matter of backbiting in the community, the act in itself is not backbiting. Indeed, the believer is doing his duty by reporting the matter to the Assembly. Sometimes when such a report is given to the Assembly, the person reporting may be bound by a promise of confidentiality not to reveal the identity of the original source of the information; in such a case the Assembly cannot require the believer to disclose the source.

Universal House of Justice to a Local Spiritual Assembly, 9 October 1976

Any information which comes to the notice of an Assembly member, solely by reason of his membership on that Assembly must not be divulged by that member, even though the Assembly itself may later decide to share it.

Universal House of Justice, NSA USA - Developing Distinctive Bahá’í Communities