The Interbellum Constitution: Union, Commerce, and Slavery in the Age of Federalisms
A synthesis of legal, political, and social history to show how the post-founding generations were forced to rethink and substantially revise the U.S. constitutional vision.
Between 1815 and 1861, American constitutional law and politics underwent a profound transformation. These decades of the Interbellum Constitution were a foundational period of both constitutional crisis and creativity.
The Interbellum Constitution was a set of widely shared legal and political principles, combined with a thoroughgoing commitment to investing those principles with meaning through debate. Each of these shared principles—commerce, concurrent power, and jurisdictional multiplicity—concerned what we now call “federalism,” meaning that they pertain to the relationships among multiple levels of government with varying degrees of autonomy. Alison L. LaCroix argues, however, that there existed many more federalisms in the early nineteenth century than today’s constitutional debates admit.
As LaCroix shows, this was a period of intense rethinking of the very basis of the U.S. national model—a problem debated everywhere, from newspapers and statehouses to local pubs and pulpits, ultimately leading both to civil war and to a new, more unified constitutional vision. This book is the first that synthesizes the legal, political, and social history of the early nineteenth century to show how deeply these constitutional questions dominated the discourse of the time.
Praise for the book
“for my constitutional law and history freaks out there, this book is sick as hell” (on Bluesky)
“Alison LaCroix’s invaluable book is a fount of information and brilliant insights about a grievously neglected period of American constitutional development. It is often gripping in the stories it relates. This is truly essential reading.”
“Few constitutional histories are as impressive and engaging as The Interbellum Constitution. . . . LaCroix’s mastery of the historian’s craft in this book is extraordinary. Each chapter is full of interesting details about the colorful characters and events it chronicles.” (in Balkinization)
“No scholar is better equipped to challenge our understanding of the history of federalism than Alison LaCroix. In this pioneering study, she recovers the spirited, contingent, decades-long argument that shaped an era that most constitutional historians have dismissed as uneventful. Essential reading.”
“A brilliant, alternately rollicking and harrowing account of the law in action in the nineteenth-century United States. Prodigiously researched and bristling with startling revisionist arguments, this book is far and away the best account of the roiling world of American federalism in the crucial decades between the War of 1812 and the Civil War. The Interbellum Constitution carries urgent lessons for the emerging federal-state battles of our times.”
“A new history of federalism in the early United States . . . [that] contextualizes and expands constitutional debates today.”
Academic Reviews
Aaron N. Coleman, “Constitutional Imagination in the “Long Founding,”” Law & Liberty, 2024.
LaCroix’s Interbellum Constitution might be the most important constitutional history of the period ever written, revealing a vibrancy and complexity too overlooked. Anyone seeking to apply the constitutional history of 1815–60 now has considerably muddier waters to paddle through. The Interbellum Constitution is history done right.
Aaron Hall, “On Constitutional Romance and Federalisms Long Forgotten: A Review Essay,” American Journal of Legal History, 2024.
LaCroix makes the Interbellum Constitution a discrete site of inquiry, where the Constitution in practice was transformed through argument. [This book will] give readers new resources to wrestle with how the United States has been governed not only by Constitution-derived institutions but also through heartfelt ideas about what the Constitution means.
Annette Gordon-Reed, ““Federalisms” and Union: The Interbellum Constitution,” The University of Chicago Law Review, 2024.
“The Interbellum Constitution reminds us of the important insights that have helped transform the historiography of the early American Republic, of slavery, and of relations between European settlers and Indigenous Peoples. . . . By mining the archive for information, [LaCroix] expands our understanding of the range of ideas about union, federalism, and sovereignty.”
Steve Vladeck, “The Interbellum Circuit Justices,” JOTWELL, 2025
“[I]n her magisterial new history of the constitutional debates of the era, legal historian Alison LaCroix expands her (and our) horizons beyond the modest contributions of the Supreme Court of the [interbellum] era and to the broader debates that played out on the ground … LaCroix’s book documents the reality of a “federalism of fractals” that was far more nuanced and jurisdictionally interdependent than the most famous Supreme Court decisions might suggest … The Interbellum Constitution is first-rate legal history and constitutional law scholarship.”
Alison LaCroix on How History Rhymes at the Supreme Court
Related Scholarship from Professor LaCroix
“Dispatches From Amendment Valley,” California Law Review, 2025.
The early nineteenth century was not a hiatus in constitution-making when one considers the ferment surrounding state constitutions. Striking differences existed between the American political world of 1804, still reeling from Thomas Jefferson’s controversial election in the “revolution of 1800,” and the post-Emancipation Proclamation, post-Appomattox world of December 1865.
“The Twin Peaks Fable of American Constitutionalism” Boston University Law Review, 2025.
The question hovering over the conference room in Philadelphia might have been paraphrased as, “Why does the Supreme Court suddenly seem to care about the history of the early American republic?” … [An] answer, one that is both more hopeful and more accurate, is: to the extent that the Court has adopted originalism as its guiding interpretive method, it seeks content stripped of context. What we the historians can provide to the Court, however, is both content and context. There is no way for historians, consistent with our professional duty, to provide context-free content.