The Civil War was widely recognized, at the time and since, as a moment of popular constitutionalism, at least in so far as the Supreme Court was made suddenly less powerful as an interpreter of the Constitution on the eve of the war. The Court was largely marginalized on constitutional questions during the war, in large part as a result of the Dred Scott Case, which Charles Evans Hughes described as one of the great "self-inflicted wounds" in the history of the Supreme Court.
If today, in a time of war, we look readily to the courts to ultimately delineate who is and who is not an "enemy combatant," to determine what process detainees are due, and to decide what is torture and what is not, the Civil War is an instance when wartime constitutional decisions were made in the relative absence of a powerful Supreme Court and even in defiance of it. The Civil War has an arguably unique role inside the history of popular constitutionalism. It is a valuable test case, a sort of trial run for a popular constitutional regime that operated in a time of terrible crisis alongside a marginalized Supreme Court, just as a spate of new and urgent constitutional questions demanded immediate resolution.
Daniel W. Hamilton,
Popular Constitutionalism in the Civil War: A Trial Run,
Chi.-Kent L. Rev.
Available at: https://scholarship.kentlaw.iit.edu/cklawreview/vol81/iss3/10