Jeff Rosen argues today that President Obama would likely win a court challenge if he asserted 14th Amendment prerogative to ignore the debt ceiling. I certainly don't know the law well enough to form a strong opinion about the legal merits. (And Jeff's article concerns the prospects of success more than the actual legal merits.) But it is worth pointing out that Obama's thinking here may reflect a short-term calculation that's not in the national interest.
As I argue in my TRB column, the debt ceiling fight represents the discovery of a powerful weapon for the opposition party, one that poses a dire financial and even political risk to the United States. Obama has an incentive to get through this crisis, and he has reason to favor compromise over a legal fight. Perhaps he thinks that asserting 14th Amendment cover to ignore the debt ceiling would provoke a public backlash, or even impeachment.
The problem is that, even if we get through this crisis with little damage, the debt ceiling is still sitting there, a weapon that will one day explode. Indeed, if there's one good reason to downgrade U.S. debt, it's that House Republicans have discovered a kind of doomsday device that, if not used this time, will probably be used eventually. Any use of the debt ceiling to extort policy concessions will encourage subsequent uses.
The only way to actually defuse the long-term threat is to eliminate the debt ceiling vote, which is a completely unnecessary relic. Doing so would provide long-term benefits, while the political costs would be born entirely by Obama. That may explain his reticence. Or possibly his advisors' legal judgment simply differs from Jeff's. There is legitimate disagreement here. In any case, it's worth keeping in mind that fact that Obama's political incentive structure on this issue doesn't fully line up with the national good.