cable to law enforcement materials, as opposed to purely administrative materials, only if disclosure of those materials would risk circumvention of the law or of agency regulations. Crooker v. Bureau of Alcohol, Tobacco, & Firearms, 670 F.2d 1051, 1074 (D.C.Cir.1981). Thus, under both the (b)(2) and the (b)(7)(E) exemptions, the agency must establish that releasing the withheld materials would risk circumvention of the law.
PHE exhausted its administrative remedies and brought suit to compel disclosure. Both the FBI and the NOEU moved for summary judgment. The FBI submitted the affidavit of Special Agent Angus Llewellyn in support of its motion; the NOEU submitted the affidavit of Marshall Williams, the senior attorney for the Department’s Information Services Unit. PHE cross-moved for summary judgment.
The district court granted summary judgment in favor of both defendants, concluding that the government’s uncontra-dicted affidavits demonstrate that the redacted material fell within the claimed exemptions. PHE appealed. On appeal, PHE raises two issues. First, it claims that the record and the affidavits provide an insufficient basis for the district court’s determination that disclosure of the withheld material presents a risk of circumvention of the law. Second, PHE claims the district court erred in failing to conduct an in camera review of the redacted information.
II.
“[Djisclosure, not secrecy, is the dominant objective” of the FOIA. Department of Air Force v. Rose, 425 U.S. 352, 361, 96 S.Ct. 1592, 1599, 48 L.Ed.2d 11 (1976). An agency that chooses to withhold requested information bears the burden of justifying its decision. King v. United States Dep’t of Justice, 830 F.2d 210, 217 (D.C.Cir.1987). A district court may grant summary judgment to the government in a FOIA case only if “the agency affidavits descidbe the documents withheld and the justifications for nondisclosure in enough detail and with sufficient specificity to demonstrate that material withheld is logically within the domain of the exemption claimed.” Id. Because only the agency knows the substance of the withheld information, the agency affidavits have immense significance in a FOIA case. Both the court and the requester must look to the affidavits for an explanation of the agency’s decision to withhold information. Consequently, an affidavit that contains merely a “categorical description of redacted materials coupled with categorical indication of anticipated consequences of disclosure is clearly inadequate.” Id. at 224; see also Kiraly v. FBI, 728 F.2d 273, 277 (6th Cir.1984); Church of Scientology v. United States Dep’t of the Army, 611 F.2d 738, 743 (9th Cir.1979).
Here, PHE claims that the government affidavits fail to support a finding that release of the withheld information would create a risk of circumvention of the law, and, therefore, the government has not carried its burden of demonstrating that the redacted material meets the criteria of exemptions (b)(2) and (b)(7)(E) of the FOIA. We disagree with PHE with respect to the FBI’s affidavit but conclude that the affidavit submitted by the NOEU is inadequate.
A. The FBI Affidavit
The FBI identified a sixteen page section of its multi-volume FBI Manual as relevant to PHE’s request. The section, entitled “Interstate Transportation of Obscene Matter,” contained a description of federal statutory provisions relating to the transportation of obscene matter,3 an analysis of the elements of the crime, over-all policy discussions and a discussion of jurisdiction, investigative procedures and venue. The FBI segregated a few short portions of the section (totalling approximately one page) that it considered non-releasable. It disclosed the rest — almost 15 of the 16 pages — to PHE.
The Llewellyn affidavit submitted in support of the FBI notes that one portion
3
See 18 U.S.C. §§ 1462, 1464-1465, 2251-2254.