Today the U.S. Supreme Court upheld a federal law that allows indefinite civil commitment of federal prisoners who have completed their sentences but are deemed "sexually dangerous." The Court, which in 1997 rejected a challenge to a similar Kansas law based on the Double Jeopardy, Due Process, and Ex Post Facto Clauses, did not deal with the usual constitutional objections in this case. Instead it addressed the question of whether the federal government, as opposed to the states, is authorized to detain people based on sex crimes they might commit in the future. The seven-justice majority concluded that it is, finding that civil commitment of "sexually dangerous" prisoners is a "necessary and proper" means of "carrying into execution" the federal government's enumerated powers. Yet the majority opinion by Justice Stephen Breyer never identifies the powers that provide the authority for this law. The omission is telling, especially since all nine justices agree that the Necessary and Proper Clause does not give Congress any independent powers.

Instead of citing specific powers, Breyer says the civil commitment law is justified by whatever enumerated powers underlie the federal criminal statutes that sexually dangerous prisoners are convicted of violating. Three of the five prisoners in this case, for example, were convicted of possessing child pornography, which Congress banned based on its authority to "regulate commerce…among the several states." Other cases might involve people whose crimes were treated as federal offenses because of a case-specific connection to interstate commerce, such as a bias-motivated assault committed with a baseball bat manufactured in another state. (I kid you not.) As Breyer notes, "the Constitution…nowhere speaks explicitly about the creation of federal crimes beyond those related to 'counterfeiting,' 'treason,' or 'Piracies and Felonies committed on the high Seas' or 'against the Law of Nations.'" But that has not stopped Congress from criminalizing a wide range of offenses (including many already addressed by state laws), based on thin or nonexistent constitutional pretexts.

Rather than questioning the constitutional basis for the criminal statues on which the civil commitment law relies, dissenting Justice Clarence Thomas (joined by Antonin Scalia) argues that the law "is aimed at protecting society from acts of sexual violence, not toward 'carrying into Execution' any enumerated power or powers of the Federal Government." Even if we assume the validity of the criminal statutes, civil commitment of "sexually dangerous" prisoners is not necessary to carry them out. The criminal statute has been fully executed at the point where someone convicted of violating it completes the sentence it prescribes, which is precisely when civil commitment takes effect. "The statute," Thomas notes, "therefore authorizes federal custody over a person at a time when the Government would lack jurisdiction to detain him for violating a criminal law that executes an enumerated power."

As further evidence that the authority to commit a "sexually dangerous" prisoner after he finishes his term does not flow from the authority to criminalize his offense, Thomas notes that the offense need not be a sex crime. One-fifth of the cases have involved prisoners who were not convicted of a federal offense involving sexual violence. Someone serving time for mail fraud or tax evasion could be be treated as a "sexually dangerous" prisoner if the government presents "clear and convincing evidence" of a tendency to commit sex crimes, which need not include a criminal conviction. Furthermore, Thomas writes, "the definition of a 'sexually dangerous person'…does not require the court to find that the person is likely to violate a law executing an enumerated power in the future." In other words, the law is only tenuously related to federal criminal statutes, which themselves may be only tenuously related to an enumerated power.

"No enumerated power…expressly delegates to Congress the power to enact a civil-commitment regime for sexually dangerous persons," Thomas writes, "nor does any other provision in the Constitution vest Congress or the other branches of the Federal Government with such a power….The Constitution does not vest in Congress the authority to protect society from every bad act that might befall it." He warns that the majority's opinion, which requires no more than a "rational" connection between a federal law and the enumerated power to which it is allegedly related (and which in this case is not even cited), "comes perilously close to transforming the Necessary and Proper Clause into a basis for the federal police power that 'we always have rejected.'"

The decision is here. Previous coverage of the case here and here.