J B delivered the opinion of the Court.
A federal civil-commitment statute authorizes the Department of Justice to detain a mentally ill, sexually dangerous federal prisoner beyond the date the prisoner would otherwise be released. 18 U.S.C. § 4248. We have previously examined similar statutes enacted under state law to determine whether they violate the Due Process Clause. See Kansas v. Hendricks, 521 U.S. 346, 356–358 (1997); Kansas v. Crane, 534 U.S. 407 (2002). But this case presents a different question. Here we ask whether the Federal Government has the authority under Article I of the Constitution to enact this federal civil-commitment program or whether its doing so falls beyond the reach of a government "of [p130] enumerated powers." McCulloch v. Maryland, 4 Wheat. 316, 405 (1819). We conclude that the Constitution grants Congress the authority to enact § 4248 as "necessary and proper for carrying into Execution" the powers "vested by" the "Constitution in the Government of the United States." Art. I, § 8, cl. 18.
I
The federal statute before us allows a district court to order the civil commitment of an individual who is currently "in the custody of the [Federal] Bureau of Prisons," § 4248, if that individual (1) has previously "engaged or attempted to engage in sexually violent conduct or child molestation," (2) currently "suffers from a serious mental illness, abnormality, or disorder," and (3) "as a result of" that mental illness, abnormality, or disorder is "sexually dangerous to others," in that "he would have serious difficulty in refraining from sexually violent conduct or child molestation if released," §§ 4247(a)(5)–(6).
In order to detain such a person, the Government (acting through the Department of Justice) must certify to a federal district judge that the prisoner meets the conditions just described, i.e., that he has engaged in sexually violent activity or child molestation in the past and that he suffers from a mental illness that makes him correspondingly dangerous to others. § 4248(a). When such a certification is filed, the statute automatically stays the individual's release from prison, ibid., thereby giving the Government an opportunity to prove its claims at a hearing through psychiatric (or other) evidence, §§ 4247(b)–(c), 4248(b). The statute provides that the prisoner "shall be represented by counsel" and shall have "an opportunity" at the hearing "to testify, to present evidence, to subpoena witnesses on his behalf, and to confront and cross-examine" the Government's witnesses. §§ 4247(d), 4248(c).
If the Government proves its claims by "clear and convincing evidence," the court will order the prisoner's continued [p131] commitment in "the custody of the Attorney General," who must "make all reasonable efforts to cause" the State where that person was tried, or the State where he is domiciled, to "assume responsibility for his custody, care, and treatment." § 4248(d); cf. Sullivan v. Freeman, 944 F.2d 334, 337 (CA7 1991). If either State is willing to assume that responsibility, the Attorney General "shall release" the individual "to the appropriate official" of that State. § 4248(d). But if, "notwithstanding such efforts, neither such State will assume such responsibility," then "the Attorney General shall place the person for treatment in a suitable [federal] facility." Ibid.; cf. § 4247(i)(A).
Confinement in the federal facility will last until either (1) the person's mental condition improves to the point where he is no longer dangerous (with or without appropriate ongoing treatment), in which case he will be released; or (2) a State assumes responsibility for his custody, care, and treatment, in which case he will be transferred to the custody of that State. §§ 4248(d)(1)–(2). The statute establishes a system for ongoing psychiatric and judicial review of the individual's case, including judicial hearings at the request of the confined person at 6-month intervals. §§ 4247(e)(1)(B), (h).