Read the whole thing, don't rush. It's important.
See this specific point on page 4:
the law enforcement privilege, which protects the contents of open (and sometimes closed) law enforcement files, including communications related to investigative and prosecutorial decisionmaking.
"The executive privileges may appropriately be treated as distinct, not only because of the different communications they protect, but also because the privileges appear to arise from different sources of law, with some more firmly established in judicial precedent than others. In short, the different privileges apply with different strengths and, in the congressional context, are balancedagainst Congress’s Article I powers differently. For example, courts have “traditionally shown the utmost deference” to presidential claims of a need to protect military or diplomatic secrets.5F22 The President’s more generalized interest in the confidentiality of his other communications, though arising implicitly from the Constitution, has not been “extended this high degree of deference.”23The other privileges have been given less weight, and must be assessed differently in the face of an exercise of Congress’s investigative powers. For example, when compared to the presidential communications privilege, the deliberative process privilege is more easily overcome by Congress and “disappears altogether when there is any reason to believe government misconduct occurred.”24 Its legal source also appears to be different from the presidential communications privilege, as it arises “primarily” from the common law,25 but may have a “constitutional dimension.”26 Least potent are those executive privileges that arise purely from the common law, 19 See Dep’t of Justice, Office of Legal Counsel, Protective Assertion of Executive Privilege Over Unredacted Mueller Report and Related Investigative Files, 43 Op. O.L.C. 374 (2019).20 See 8 Op. O.L.C. 101, 116 (reasoning that “[t]he scope of executive privilege includes several related areas”); 13 Op. O.L.C. 153, 154 (reasoning that “the executive branch's interest in keeping the information confidential” is “usually discussed in terms of "'executive privilege’”).21 See H. COMM. ON OVERSIGHT AND GOV’T REFORM, 110TH CONG., REP. ON PRESIDENT BUSH’S ASSERTION OF EXECUTIVE PRIVILEGE IN RESPONSE TO THE COMMITTEE SUBPOENA TO ATTORNEY GENERAL MICHAEL B. MUKASEY 8 (Comm. Print 2008) (“The Attorney General's argument that the subpoena implicates the ‘law enforcement component’of executive privilege is equally flawed. There is no basis to support the proposition that a law enforcement privilege, particularly one applied to closed investigations, can shield from congressional scrutiny information that is important for addressing congressional oversight concerns. The Attorney General did not cite a single judicial decision recognizing this alleged privilege.”); H.R. REP. NO. 105-728, at 16 n. 43 (1998) (“As the D.C. Circuit has recently held, the doctrine of executive privilege which arises from the constitutional separation of powers applies only to decisionmaking of the President. Since the subject of the Committee’s subpoena is not one that does (or legally could) involve Presidential decisionmaking, no constitutional privilege could be invoked here.”) (citations omitted).22 United States v. Nixon, 418 U.S. 683, 710 (1974).23 Id. at 711. 24 In re Sealed Case, 121 F.3d 729, 746 (D.C. Cir. 1997). Given its broad scope, the deliberative process privilege is“the most frequent form of executive privilege raised.” Id. at 737. 25 In In re Sealed Case, the D.C. Circuit determined that “the deliberative process privilege is primarily a common law privilege,” but that “
ome aspects of the privilege, for example the protection accorded the mental processes of agency officials, have roots in the constitutional separation of powers.” 121 F.3d at 745, 737 n.4. See also Protect Democ. Project v. NSA, 10 F.4th 879, 885 (D.C. Cir. 2021) (“The deliberative process privilege is primarily a common law privilege . . . .”). 26 Comm. on Oversight & Gov’t Reform v. Lynch, 156 F. Supp. 3d 101, 104 (D.D.C. 2016). The scope and source of the law enforcement privilege is unclear, particularly when asserted in the context of congressional investigations where committees have voiced consistent objections to its use. Congress has previously viewed the executive branch’s position on the confidentiality of law enforcement information as a nondisclosure “policy” rather than a constitutionally Executive Privilege and Presidential Communications: Judicial PrinciplesCongressional Research Service 5which have generally been viewed, at least by Congress, as legally insufficient to justify noncompliance with a congressional subpoena."
