Samuel Alito

“ Just as it is necessary and proper for Congress to provide for the apprehension of escaped federal prisoners, it is necessary and proper for Congress to provide for the civil commitment of dangerous federal prisoners who would otherwise escape civil commitment as a result of federal imprisonment. ”

“ These federal prisoners, having been held for years in a federal prison, often had few ties to any State; it was a matter of speculation where they would choose to go upon release; and accordingly no State was enthusiastic about volunteering to shoulder the burden of civil commitment.
The Necessary and Proper Clause does not give Congress carte blanche. Although the term "necessary" does not mean "absolutely necessary" or indispensable, the term requires an "appropriate" link between a power conferred by the Constitution and the law enacted by Congress. ”

“ The statute recognizes that, in many cases, no State will assume the heavy financial burden of civilly committing a dangerous federal prisoner who, as a result of lengthy federal incarceration, no longer has any substantial ties to any State. ”