If the filmmaker Whit Stillman thinks that the scions of the Yankees who built this country have lost their drive and ingenuity, he never met Eli Whitney Debevoise II. A descendant of the cotton gin’s inventor and grandson of Debevoise & Plimpton’s founder, Whit Debevoise is an inspired tinkerer in his own right, in the abstract but no less practical field of sovereign finance.

In a 2012 ruling on Argentine bonds, the U.S. Court of Appeals for the Second Circuit gave a surprise reading to the Latin phrase “pari passu,” which places all creditors on equal footing. The clause had long been regarded as boilerplate. In NML v. Argentina, the Second Circuit read it to require that a nation servicing restructured bonds must pay in full the holdouts who had refused to trade in their bonds at a discount. Who then would trade in their bonds next time? Many predicted that sovereign restructuring would grind to a halt. Debevoise just rolled up his sleeves.