The Supreme Court will decide whether a federal law that permits the Justice Department to hold "dangerous" sex offenders past their sentences is Constitutional. The law was passed in 2006 and allows the Justice Department to hold sexually violent or mentally ill sex offenders past their completed sentence date.
Several prisoners have challenged the law, claiming Congress has assumed the police power over public health and safety, which is a power belonging to the states. A widespread federal law related to sex offenders is arguably not within Congressional reach, because it is general law related to health and safety and does not relate to a specific federal power.
During oral argument, the Justices seemed split. Justice Scalia felt convinced Congress had overstepped its powers, but Justice Alito appeared sympathetic to the law.
Justices Hear Sex-Offender Case | The Wall Street Journal