The Board shall open every portion of every meeting of the agency for public observation except where the agency determines that such portion or portions of the meeting or the disclosure of such information is likely to:

(a) Disclose matters that are:

(1) Specifically authorized under criteria established by an Executive order to be kept secret in the interests of national defense or foreign policy, and

(2) In fact properly classified pursuant to such Executive order;

(b) Relate solely to the internal personnel rules and practice of the agency;

(c) Disclose matters specifically exempted from disclosure by statute: Provided, that such statute:

(1) Requires that the matters be withheld from the public in such manner as to leave no discretion on the issue, or

(2) Established practical criteria for withholding or refers to particular types of matters to be withheld;

(d) Disclose trade secrets and commercial or financial information obtained from a person and privileged or confidential;

(e) Involve accusing any person of a crime, or formally censuring any person;

(f) Disclose information of a personal nature where disclosure would constitute a clearly unwarranted invasion of personal privacy;

(g) Disclose investigatory records compiled for law enforcement purposes, or information which if written would be contained in such records, but only to the extent that the production of such records or information would:

(1) Interfere with enforcement proceedings,

(2) Deprive a person of a right to a fair trial on an impartial adjudication,

(3) Constitute an unwarranted invasion of personal privacy,

(4) Disclose the identity of a confidential source and, in the case of a record compiled by a criminal law enforcement authority in the course of a criminal investigation, or by an agency conducting a lawful national security intelligence investigation, confidential source,

(5) Disclose investigative techniques and procedures, or

(6) Endanger the life or physical safety of law enforcement personnel;

(h) Disclose information, the premature disclosure of which would be likely to significantly frustrate implementation of a proposed agency action. This shall not apply in any instance where the Board has already disclosed to the public the content or the nature of its proposed action, or where the Board is required by law to make such disclosures on its own initiative prior to taking final Board action on such proposal; or

(i) Specifically concern the Board's issuance of a subpoena, or the Board's participation in a civil action or proceeding, an action in a foreign court or international tribunal, or an arbitration, or the initiation, conduct or disposition by the Board of a particular case of formal agency adjudication, or otherwise involving a determination on the record after opportunity for a hearing.