State sovereign immunity is a sort of constitutional comet, streaking across the sky once a century to the amazement and consternation of legal commentators. The comet’s appearance has usually coincided with major state debt crises: The Revolutionary War debts brought us Chisholm v. Georgia and the Eleventh Amendment, and the Reconstruction debts brought us Hans v. Louisiana and the Amendment’s extension to federal question cases. This essay argues that much of our law of state sovereign immunity, including its odd fictions and otherwise-incongruous exceptions, can be understood as an effort to maintain immunity’s core purpose — protecting the states from potentially crippling financial liability on their debts — while at the same time main...