Abstract: In the last twenty years, a consensus has developed among courts and scholars that customary international law has the status of federal common law. We label this consensus the "modern position." Courts have endorsed the modern position primarily to support their conclusion that international human rights lawsuits between aliens "arise under" the laws of the United States for purposes of Article III of the Constitution. Scholars have pushed the consequences of the modern position further by arguing that customary international law preempts inconsistent state law under the Supremacy Clause, binds the President under the Take Care Clause, and even supersedes prior inconsistent federal legislation. In this Article, we question the modern position's historical validity, and show that its recent rise to orthodoxy has been accompanied by little critical scrutiny. We then question contemporary arguments for the modern position and show how these arguments depart form basic understandings about American representative democracy, federal common law, separation of powers, and federalism. We conclude that, in the absence of authorization by the federal political branches, customary international law should not have the status of federal law. This conclusion requires less change in judicial practice than might commonly be thought. Nonetheless, the story of the modern position's rise and continued influence presents cautionary lessons for a democratic society increasingly governed by international law.