‘The most‐favored‐nation clause in American commercial treaties, as conditionally interpreted and applied by the United States, has probably been the cause in the last century of more diplomatic controversy, more variations in construction, more international ill‐feeling, more conflict between international obligations and municipal law and between judicial interpretation and executive practice. more confusion and uncertainty of operation, than have developed under all the unconditional most‐favored‐nation pledges of all other countries combined’— Jacob Viner, in theJournal of Political Econom