Title: States' rights
Content:  Over following decades, another central dispute over states' rights moved to the forefront. The issue of slavery polarized the union, with the Jeffersonian principles often being used by both sides—anti-slavery Northerners, and Southern slaveholders and secessionists—in debates that ultimately led to the American Civil War. Supporters of slavery often argued that one of the rights of the states was the protection of slave property wherever it went, a position endorsed by the U.S. Supreme Court in 1857 Dred Scott decision. In contrast, opponents of slavery argued that the non-slave-states' rights were violated both by that decision and by the Fugitive Slave Law of 1850. Exactly which—and whose—states' rights were the casus belli in the Civil War remain in controversy.
Title: American Civil War
Content:  A long running dispute over the origin of the Civil War is to what extent states' rights triggered the conflict. The consensus among historians is that the Civil War was not fought about states' rights. But the issue is frequently referenced in popular accounts of the war and has much traction among Southerners. The South argued that just as each state had decided to join the Union, a state had the right to secede—leave the Union—at any time. Northerners (including pro-slavery President Buchanan) rejected that notion as opposed to the will of the Founding Fathers, who said they were setting up a perpetual union. Historian James McPherson points out that even if Confederates genuinely fought over states' rights, it boiled down to states' right to slavery. McPherson writes concerning 
Title: American Civil War
Content:  rights and other non-slavery explanations: "While one or more of these interpretations remain popular among the Sons of Confederate Veterans and other Southern heritage groups, few professional historians now subscribe to them. Of all these interpretations, the states'-rights argument is perhaps the weakest. It fails to ask the question, states' rights for what purpose? States' rights, or sovereignty, was always more a means than an end, an instrument to achieve a certain goal more than a principle." Before the Civil War, the Southern states used federal powers in enforcing and extending slavery at the national level, with the Fugitive Slave Act of 1850 and Dred Scott v. Sandford decision. The faction that pushed for secession often infringed on states' rights. Because of the overrepresentation of pro-slavery factions in 
Title: Origins of the American Civil War
Content:  Arthur M. Schlesinger Jr. noted that the states' rights "never had any real vitality independent of underlying conditions of vast social, economic, or political significance." He further elaborated: "From the close of the nullification episode of 1832–1833 to the outbreak of the Civil War, the agitation of state rights was intimately connected with a new issue of growing importance, the slavery question, and the principal form assumed by the doctrine was that of the right of secession. The pro-slavery forces sought refuge in the state rights position as a shield against federal interference with pro-slavery projects. ... As a natural consequence, anti-slavery legislatures in the North were led to lay great stress on the 
Title: Historiographic issues about the American Civil War
Content:  slavery but states' rights. According to Stampp, Stephens became one of the most ardent defenders of the Lost Cause. The historian William C. Davis also mentioned inconsistencies in Southern states' rights arguments. He explained the Confederate Constitution's protection of slavery at the national level as follows:"To the old Union they had said that the Federal power had no authority to interfere with slavery issues in a state. To their new nation they would declare that the state had no power to interfere with a federal protection of slavery. Of all the many testimonials to the fact that slavery, and not states rights, really lay at the heart of their movement, this was the most eloquent of all."
Title: Origins of the American Civil War
Content:  at the national level as follows: "To the old Union they had said that the Federal power had no authority to interfere with slavery issues in a state. To their new nation they would declare that the state had no power to interfere with a federal protection of slavery. Of all the many testimonials to the fact that slavery, and not states rights, really lay at the heart of their movement, this was the most eloquent of all." W.C. Davis also stated that: "In fact, the state rights defense of secession in 1860–1861 did not really appear in force 
Title: Northern United States
Content:   During the American Civil War, the Northern United States comprised the U.S. states that supported the United States of America (the Union states); in this context, "The North" is synonymous with "the Union," while "The South" refers to the states that seceded from the U.S. in order to form the Confederate States of America. There is, however, some historical disagreement as to exactly which states comprised "The North" in the context of the Civil War as five slave-holding states remained with the union: the Border states of Missouri, Kentucky, West Virginia, Maryland, and Delaware, alongside the disputed Indian Territory; depending on the source, these states and territories may be included in either region.
Title: States' rights
Content:  of 18th-century Whig lawyers. Taylor believed that evidence from American history gave proof of state sovereignty within the union, against the arguments of nationalists such as U.S. Chief Justice John Marshall. Another states' rights dispute occurred over the War of 1812. At the Hartford Convention of 1814–15, New England Federalists voiced opposition to President Madison's war, and discussed secession from the Union. In the end they stopped short of calls for secession, but when their report appeared at the same time as news of the great American victory at the Battle of New Orleans, the Federalists were politically ruined.
Title: Historiographic issues about the American Civil War
Content:  Questions such as whether the Union was older than the states or the other way around fueled the debate over states' rights. Whether the federal government was supposed to have substantial powers or whether it was merely a voluntary federation of sovereign states added to the controversy. According to historian Kenneth M. Stampp, each section used states' rights arguments when convenient, and shifted positions when convenient. Stampp mentioned Confederate Vice President Alexander Stephens' A Constitutional View of the Late War Between the States as an example of a Southern leader who said that slavery was the "cornerstone of the Confederacy" when the war began, and then said, after the South was defeated, that the war was not 
Title: States' rights
Content:  South Carolina Nullifiers quoted Madison in their defense of states' rights. But Madison feared that the growing support for this doctrine would undermine the union and argued that by ratifying the Constitution states had transferred their sovereignty to the federal government. The most vociferous supporters of states' rights, such as John Randolph of Roanoke, were called "Old Republicans" into the 1820s and 1830s. Tate (2011) undertook a literary criticism of a major book by John Taylor of Caroline, New Views of the Constitution of the United States. Tate argues it is structured as a forensic historiography modeled on the 

Question: who supported states rights during the civil war?
Answer: the Confederacy.