Argus Leader (P), a South Dakota newspaper, filed a FOIA request for data collected by the United States Department of Agriculture. The USDA administers the Supplemental Nutrition Assistance Program. P asked the USDA for the names and addresses of all retail stores that participate in SNAP and each store’s annual SNAP redemption data from fiscal years 2005 to 2010, which we refer to as “store-level SNAP data.” USDA released the names and addresses of the participating stores but declined to disclose the requested store-level SNAP data. The USDA invoked FOIA’s Exemption 4, which shields from disclosure “trade secrets and commercial or financial information obtained from a person and privileged or confidential.” 5 U. S. C. §552(b)(4). P sued the USDA to compel release of the store-level SNAP data. The Eighth Circuit has engrafted onto Exemption 4 a so-called “competitive harm” test, under which commercial information cannot be deemed “confidential” unless disclosure is “likely . . . to cause substantial harm to the competitive position of the person from whom the information was obtained.” The district court held a two-day bench trial. Witnesses for the USDA testified that retailers closely guard store-level SNAP data and that disclosure would threaten stores’ competitive positions. They explained that retailers use models of consumer behavior to help choose new store locations and to plan sales strategies. Competitors’ estimated sales volumes represent an important component of these models and can be time-consuming and expensive to generate. A model’s accuracy and utility increase significantly if it includes a rival’s actual sales data rather than mere estimates. Thus the disclosure of store-level SNAP data could create a windfall for competitors. P contended that any competitive harm associated with disclosure would not be substantial. The court ordered disclosure. The USDA declined to appeal. D intervened and appealed. D argued that the court should discard the “substantial competitive harm” test and apply instead the ordinary public meaning of the statutory term “confidential.” The appeals court affirmed. D appealed.