It was a humbling experience for the chief executive of the world’s most valuable company. Hauled before a Senate panel, Apple’s Tim Cook had to explain how an American company whose American engineers had created the iPhone and the iPad was able to avoid paying any taxes on billions of dollars in profits generated by those products — not to United States, not to any country. The only defense the Cook could conjure up for Apple “stateless” income was that it was all perfectly legal.

A few miles away in Arlington, a 55-year-old economist named Marty Sullivan sat on a folding metal chair at a card table in the garage of his modest brick home and watched the hearing unfold on his laptop computer. Sullivan is one of those unheralded members of the permanent Washington establishment who make things work, at least when the politicians let them. And for two decades, from the same home office, Sullivan has been exposing the tax-dodging schemes of multinational corporations in the columns of Tax Notes, a must-read publication for tax lawyers, accountants and policy wonks.