Amateur radio operators, represented by the American Radio Relay League, Inc. (ARRL) (plaintiff), believed that broadband Internet data transmissions could cause spectrum interference with radio communications. The Federal Communications Commission (FCC) (defendant) proposed rules to regulate the broadband transmissions. The FCC based its proposal on five scientific studies. The FCC made portions of those studies available for public review but redacted internal FCC communications that summarized and critiqued the studies. The FCC claimed that, in reaching its decision, the FCC had not relied on the redacted portions. After the FCC finalized its rules, the ARRL sued the FCC in the United States Court of Appeals for the District of Columbia, contending, among other things, that the FCC had violated the Administrative Procedure Act (APA), 5 U.S.C. § 551 et seq., by not making the redacted internal communications available for public review before finalizing the rules.