This article compares the Supreme Court’s treatment of implied presidential power to its treatment of implied congressional power. The implied powers literature usually focuses on a single branch of government’s implied power or a single implied power, such as the President’s implied foreign affairs power. This article defines implied power, something generally neglected in the literature. It then compares and evaluates the Court’s treatment of Congress and the President using three concepts underlying the leading implied power cases — constitutional custom, means/ends reasoning, and the congressional stance toward presidential power (from Justice Jackson’s concurrence in Youngstown). The article closes with a case study focusing on the question of whether a sitting President has an implied power to resist indictment to illustrate how our findings help illuminate open issues. Three somewhat surprising conclusions emerge from this analysis. First, the Court gives executive branch actions much more weight than legislation that Congress has enacted and Presidents have signed in evaluating constitutional custom. Second, the Court’s presidential powers decisions depend much more heavily on judicial institutional and policy preferences than upon express or implied congressional intent. Third, the Court often does not follow McCullogh’s holding that Congress may use any means toward the ends underlying its enumerated powers, while it sometimes applies Justice Marshall’s means/ends reasoning to create fresh presidential powers. This comparison reveals a judicial tendency to imply presidential powers more generously than congressional power, even though the Constitution’s text only authorizes implied congressional power. While the Court’s preferences for presidential power over foreign affairs and states’ rights underlie many of the examined cases, we show that the Court’s preference for presidential power goes beyond the areas of national security and foreign affairs to embrace implied presidential power to avoid legal accountability domestically. We offer a preliminary evaluation of whether the Court’s approach to implied powers undermines the rule of law. We suggest that the Court has adapted the Constitution to the needs of the Cold War and later the war on terrorism, but may need to change its approach to address the wave of authoritarianism currently sweeping the globe.