Some have questioned the legitimacy of the original Constitution because they claim that the Founders supported slavery and therefore anything that they did is illegitimate. In fact, many of the Founders were quite opposed to slavery and the Constitution was a result of a compromise between states where slavery was abolished or was going to be abolished soon and states where it wasn't going to be abolished. And the result of that compromise was a system of federalism, in which states were given a great deal of power over their own citizenry. In fact, states had so much power over their own citizens that they could authorize some citizens to own other citizens and this tells us that under the original structural Constitution, states had a great deal of power and the federal government have very little power. With respect to slavery, the original Constitution adopted a view that the later Republican party would identify as freedom national, slavery local. And what they meant by that is that the Constitution, nationally, said very little if anything about slavery. Nationally, Congress was free to do pretty much whatever it wanted when it regulated the territories, when it regulated the District of Columbia, when it regulated federal institutions. It could be pro- or anti-slavery under the text of the original Constitution. Where the Constitution is pro-slavery, or at least sanctions slavery, is at the local level. It allows states to authorize slavery, if states wish to. And it allowed states to abolish slavery where they thought it was appropriate, as many states did. So that was freedom national and slavery local and essentially what the amendments to the Constitution did, the Reconstruction Amendments did, was abolish the slavery local part of this provision. This original structure was fundamentally altered after the Civil War by the adoption of the Reconstruction Amendments, the 13th, 14th, and 15th amendments, that created new federal powers to protect citizens from having their rights violated by their own state governments. The 13th amendment made slavery unconstitutional at the local level, not just at the federal level, and that's why the Republicans promoted it. They thought it was necessary to have a constitutional amendment to change the Constitution from freedom national, slavery local to a Constitution where it's freedom national and freedom local as well.