Article One and the (Un)Constitutionality of Default

In the debate on the debt ceiling standoff, some commentators claim that a default or a partial default on national debt payments would violate Section Four of the Fourteenth Amendment. There is, however, also a credible argument that a default is beyond Congress's Article One, Section Eight power "[t]o borrow money on the credit of the United States."

Chief Justice Hughes's plurality opinion in Perry v. United States developed this idea. The Chief Justice said that Section Four of the Fourteenth Amendment confirmed, rather than created, the fundamental principle that the United States was obligated to repay its debts. He explained that principle this way:

By virtue of the power to borrow money 'on the credit of the United States,' the Congress is authorized to pledge that credit as an assurance of payment as stipulated, as the highest assurance the government can give, its plighted faith. To say that the Congress may withdraw or ignore that pledge is to assume that the Constitution contemplates a vain promise; a pledge having no other sanction than the pleasure and convenience of the pledgor. This Court has given no sanction to such a conception of the obligations of our government.

          . . .

The Constitution gives to the Congress the power to borrow money on the credit of the United States, an unqualified power, a power vital to the government, upon which in an extremity its very life may depend. The binding quality of the promise of the United States is of the essence of the credit which is so pledged. Having this power to authorize the issue of definite obligations for the payment of money borrowed, the Congress has not been vested with authority to alter or destroy those obligations. 

The argument that Congress lacks the enumerated authority to default shifts the focus from 1868 to 1787-1788 and might alter the relevant conclusions, though I do not know enough about that to give an opinion.