The trouble started, as it often does, with France. Congressmen in the 1930s complained about “nations throughout this world who are not particularly friendly to Uncle Sam in a business way”. Mainly that meant the European power, which had slow-walked ratification of a tax treaty and was double-taxing Americans in the meantime. In 1934, to persuade French policymakers to pick up the pace, Congress passed a provision that is now known as Section 891. It granted the president the power to double levies on citizens and companies from countries that he judged to be overtaxing Americans.