There is now a deal over the debt limit, but President nevertheless insists that he's still looking at using the 14th Amendment in the future—apparently to decide "whether or not you need to do the debt limit every year." Motivated in part by some friendly disagreement with Michael Dorf, the President's comments seem like a good occasion for me to revisit the absence of a 14th Amendment authority to exceed the limit and respond to a few of Dorf's points.
A brief recap. There are two leading theories by which the President might declare the debt limit unconstitutional. The first leans on the Public Debt Clause of the 14th Amendment, which provides in relevant (if vague) part that "[t]he validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned." Applying this Clause as an authority gets most the most press, and it's the one that Biden himself seems to find plausible.
The second view—which I find more intriguing and which the President hasn't addressed—is Neil Buchanan and Michael Dorf's theory that the debt limit can create a kind of trilemma: If the President doesn't have enough money to satisfy spending statutes, he must (so the theory goes) either arrogate Congress's spending power or arrogate one on revenue-side authorities—taxing or borrowing.
