Probably the most startling provision of the Virginia Plan presented to the Constitutional Convention by Edmund Randolph (although most presume that it was largely James Madison's work) on May 29, 1787 is the Sixth Resolution, which, among other things, proposed to grant Congress the power to veto state legislation and to use force against a state that “fail[ed] to fulfill its duty.”
6. Resolved that each branch ought to possess the right of originating Acts; that the National Legislature ought to be impowered to enjoy the Legislative Rights vested in Congress by the Confederation & moreover to legislate in all cases to which the separate States are incompetent, or in which the harmony of the United States may be interrupted by the exercise of individual Legislation; to negative all laws passed by the several States, contravening in the opinion of the National Legislature the articles of Union; and to call forth the force of the Union agst. any member of the Union failing to fulfill its duty under the articles thereof.
In The Sacred Fire of Liberty: James Madison and the Founding of the Federal Republic, however, Lance Banning points out something I hadn't noticed: Madison expressed his doubts about the last provision – authorizing the “National Legislature” “to call forth . . . force” against a state – within forty-eight hours.
On May 31, 1787, the members of the convention, sitting as a committee of the whole, turned to “[t]he (last) clause (of Resolution 6. authorizing) an exertion of the force of the whole agst. a delinquent State.” Madison immediately moved to defer consideration because “he doubted” its “practicability,” “justice” and “efficacy”:
Mr. (Madison), observed that the more he reflected on the use of force, the more he doubted the practicability, the justice and the efficacy of it when applied to people collectively and not individually. -, A Union of the States (containing such an ingredient) seemed to provide for its own destruction. The use of force agst. a State, would look more like a declaration of war, than an infliction of punishment, and would probably be considered by the party attacked as a dissolution of all previous compacts by which it might be bound. He hoped that such a system would be framed as might render this recourse unnecessary, and moved that the clause be postponed. This motion was agreed to nem. con. [without dissent].
Seizing on the phrase in Madison's explanation doubting the provision's “justice . . . when applied to people collectively and not individually”, Prof. Banning suggests that Madison was beginning to rethink his “assumption that the Union would remain confederal in some of its essential principles” and was starting to think about “the concept that the central government should act exclusively on the people, not on the states.”
Maybe as I read on I'll become convinced, but it's hard to draw this principle out of Madison's vague explanation. After all, Madison spoke of “practicability” and “efficacy”, not just of “justice.” It's not at all clear to me why the distinction between “a declaration of war” and “an infliction of punishment” is consistent with this thesis. And Madison's last point certainly suggests that that he still conceived the union as a “compact” that might be dissolved by breach.