Holding: The Sex Offender Registration and Notification Act of 2007 makes it a crime for convicted sex offenders to fail to register with local authorities when they move to a new state. The Court rules that the Act does not apply to sex offenders moved before the Act went into effect.
Judgment: Reversed and remanded, 6-3, in an opinion by Justice Sonia Sotomayor on June 1, 2010. Justice Scalia joined in part, and filed a separate opinion concurring in part and concurring in the judgment. Justice Alito filed a dissenting opinion, joined by Justices Thomas and Ginsburg.