The United States Supreme Court reasoned,

The Framers knew the difference between doing something and doing nothing. They gave Congress the power to regulate commerce, not to compel it. Ignoring that distinction would undermine the principle that the Federal Government is a government of limited and enumerated powers. The individual mandate thus cannot be sustained under Congress’s power to “regulate Commerce.”

However, because “every reasonable construction must be resorted to, in order to save a statute from unconstitutionality,” Hooper v. California, 155 U. S. 648, 657, the question is whether it is “fairly possible” to interpret the mandate as imposing such a tax. See Crowell v. Benson, 285 U. S. 22, 62. Pp. 31–32.

A majority of the Court concluded that it was not unreasonable or impossible to construe the individual mandate as a tax, such that the mandate may not be unconstitutional.