The Nation at Sea tells a new story about the federal judiciary, and about the early United States itself. Most accounts of the nation's transformation from infant republic to world power ignore the courts. Their importance, if any, was limited to domestic politics. But the truth is that, in the critical decades following the Constitution's ratification, federal judges decided thousands of maritime cases that profoundly shaped the United States' relations with foreign nations. Judges ruled on the legality of naval captures made by European powers, regulated the conduct of American merchants, and tried pirates and slave traders who sought profit amid the turmoil of transatlantic war. Kevin Arlyck's vivid reconstruction of this forgotten history reveals how, over time, the federal courts helped realize an increasingly bold conception of American sovereignty, one that vindicated the Declaration of Independence's claim to the United States' place 'among the powers of the earth.'