In 1994, Christopher Dean (plaintiff) was found guilty of a sex offense. In 2007, Dean failed to register as a sex offender, as required by the federal Sex Offender Registration and Notification Act (SORNA), 42 U.S.C. § 16901, et seq. SORNA was enacted in July 2006, but it gave the United States Attorney General (attorney general) (defendant) the option of enforcing SORNA retroactively against persons who, like Dean, had been convicted of sexual offenses prior to SORNA’s enactment. In February 2007, the attorney general opted to implement to enforce SORNA retroactively by issuing an interim rule. However, the attorney general issued the interim rule without first applying the notice and comment procedures in the Administrative Procedure Act (APA), 5 U.S.C. § 551 et seq. The attorney general said there was good cause to bypass the time-consuming notice-and-comment procedures to immediately protect children from sexual crimes. Dean appealed his 2008 conviction, contending that the attorney general lacked good cause to issue the 2007 interim rule without notice and comment.