The War of 1812’s end heralded a new era for the courts, and for the nation. Political leaders emboldened by having fought Great Britain to a standstill were eager to lay the groundwork for a new American empire. But adventurous Americans had their own priorities, and privateering on behalf of South American revolutionary governments offered new opportunities for wartime profit. Like the British in the 1790s, Spanish and Portuguese officials demanded that the federal government suppress such freelancing. To preserve relations, the Madison and Monroe administrations dusted off a tool for suppressing maritime violence that previous administrations had largely eschewed – criminal prosecutions for piracy. But a patchwork statutory regime and popular support for South American rebels made convictions difficult to secure. At a deeper level, privateering cases raised thorny questions about the sovereign status of former colonies seeking autonomy. As Congress and the executive branch struggled to adapt to the rapidly shifting political context in the Americas, federal judges expressed renewed doubts about extending their authority onto the high seas. The renaissance of privateering threatened to derail the American imperial project just as it was getting started.