On the eve of the Supreme Court’s decision over Obamacare’s individual mandate, attention is been focused on the challengers’ argument that the mandate is outside the Commerce Power because otherwise there would be no “limiting principle” to Congress’s authority.

Certainly, the question of whether congressional authority is limited or unlimited is an important issue in the case. But another, perhaps deeper, issue is whether the Constitution’s words mean anything at all.

The Constitution grants Congress power to “regulate Commerce . . . among the several States. . . .” The word “Commerce” was designed to encompass only some designated activities: trading (buying and selling) among merchants, navigation and cargo insurance, commercial paper and finance, construction and maintenance of ports, and a few others. When the American people adopted the Constitution, if an individual was not engaged in some of those activities, then that individual was not engaged in “commerce,” and therefore Congress could not regulate him under the Commerce Clause. True, his activities might be governable under the Necessary and Proper Clause, but only if he was engaged in conduct “incidental” (subordinate and connected by custom or necessity) to “Commerce.”

In case decisions since the 1930s, the Supreme Court has, mostly through the Necessary and Proper Clause, expanded the scope of permissible regulation from commerce and its incidents to “economic activities that substantially affect commerce.” Additionally, in the 1944 case of U.S. v. South-Eastern Underwriters, the Court erroneously held that insurance is “commerce” itself, implying it could be governed under the core Commerce Clause and not merely under the Necessary and Proper component of the Commerce Power. But despite such decisions, the Court always has required that there be some activity for Congress to regulate.

As the great justice John Marshall said in Gibbons v. Ogden (1824), in a document of enumerated powers, “The enumeration presupposes something not enumerated.” Thus, when the Constitution authorized Congress to “regulate Commerce” or “punish Piracies,” it did not thereby authorize Congress to regulate or punish other activities.

Even more fundamentally, a core tenet of western philosophy, at least since Aristotle, has been that a proposition cannot embrace its opposite—that “A” does not, and cannot, include “not A.” That’s why a power to punish piracy is not a power to punish you for the decision not to engage in piracy. Otherwise, “A” would encompass “not A.” Similarly, a power to regulate commerce does not encompass a power to regulate you when you refuse to engage in commerce.

In the Obamacare litigation, the government has been arguing that health insurance is part of “commerce.” That is wrong under the Constitution’s actual meaning, but a justifiable argument for lawyers to make under post-New Deal Supreme Court jurisprudence.

But the contention that non-Commerce is “Commerce” goes much farther: It is the claim that “A” encompasses “not A.” It is an assault on the very concept of “meaning” that underlies the rule of law.