Akhil Reed Amar closes out his Yale course on the Constitution by tracing how the founding document's structure grew from a single premise, national security, and how that same system failed to stop slavery's spread. He derives bicameralism, a separate executive and judiciary, and popular ratification from the need for a government that could tax, raise armies, and bind states by treaty. He then explains why Congress never barred slavery from the territories, crediting the North's advantage partly to contingencies like Indian defeats in Ohio and Southern fear of importing enslaved people after Haiti's revolution. The argument moves through Jefferson, Jackson, and Taney's Dred Scott decision before landing on Lincoln's actual 1860 platform: no new slavery in the territories and gradual, compensated abolition modeled on how northern states had done it. The lecture sets up the Civil War amendments by showing exactly what the founders' compromise could not fix.