three distinct kinds of executive privileges

Executive privilege is, nonetheless, not a clear or unitary concept. ⁶⁶ It has encompassed claims of varying kinds.⁶⁷Tribe, in fact, comments that while it is customary to employ the phrase "executive privilege," it may be more accurate to speak of executive privileges "since presidential refusals to furnish information may be actuated by any of at least three distinct kinds of considerations, and may be asserted, with differing degrees of success, in the context of either judicial or legislative investigations."

One variety of the privilege, Tribe explains, is the state secrets privilege invoked by U.S. Presidents, beginning with Washington, on the ground that the information is of such nature that its disclosure would subvert crucial military or diplomatic objectives. Another variety is the informer’s privilege, or the privilege of the Government not to disclose the identity of persons who furnish information of violations of law to officers charged with the enforcement of that law. Finally, a generic privilege for internal deliberations has been said to attach to intragovernmental documents reflecting advisory opinions, recommendations and deliberations comprising part of a process by which governmental decisions and policies are formulated. ⁶⁸