Federal obstruction of justice statutes bar anyone from interfering with official legal proceedings based on a corrupt motive. But what about the president of the United States? The president is vested with executive power, which includes the power to control federal law enforcement. A possible view is that the statutes do not apply to the president because if they did they would violate the president's constitutional power. However, we argue that the obstruction of justice statutes are best interpreted to apply to the president, and that the president obstructs justice when his motive for intervening in an investigation is to further personal, pecuniary, or narrowly partisan interests, rather than to advance the public good. A brief tour of presidential scandals indicates that, without anyone noticing it, the law of obstruction of justice has evolved into a major check on presidential power.