New York Times:  The Debt Limit Is the Real Fiscal Cliff, by Bruce Bartlett:

In a new book, Is U.S. Government Debt Different?, Howell Jackson, a law professor at Harvard, walks through options for prioritizing government spending in the event that Republicans insist on committing financial suicide. They are all illegal or unconstitutional to one degree or another. They would require the Treasury to either abrogate Congress’s taxing power, spending power or borrowing power.

In the October issue of the Columbia Law Review, Professors Neil H. Buchanan of the George Washington University Law School and Michael C. Dorf of Cornell Law School examine the question of what a president should do when he must act and all his options are unconstitutional. They cite Abraham Lincoln’s July 4, 1861, message to Congress in support of the idea that some laws are more unconstitutional than others and the president is empowered to violate the one that is least unconstitutional when he has no other option.

Said Lincoln, “To state the question more directly, are all the laws, but one, to go unexecuted, and the government itself go to pieces, lest that one be violated?”

In the present case, of course, the one law would be the debt limit, which Professors Buchanan and Dorf say is less binding on the president than unilaterally cutting spending or raising taxes without congressional approval. Hence, if Republicans are truly mad and absolutely refuse to raise the debt limit, thereby risking default or the nonpayment of essential government bills, Professors Buchanan and Dorf believe the president would have the authority to sell bonds over and above the limit.

There are a host of practical problems any time the president is forced into uncharted constitutional territory, as Lincoln so often was. But when faced with an extortion demand from a political party that no longer feels bound by the historical norms of conduct, the president must be willing to do what has to be done.