What idea did the supporters of the states' rights doctrine promote?

Answer 1

The fundamental idea behind the "State's Rights" movement is that the United States is really a Confederation, not a Federation. The difference is subtle, but very important.

In a Federation, ultimate sovereignty is held at the national level, by the national government. That is, all parts of the nation owe sovereignty to the nation as a whole. In a federation, ultimate power rests at the national government level; while it is possible to delegate responsibilities (and authority), to other entities, the legal power to delegate sits with the federal government.

In a Confederations, the nation is composed of smaller sovereign states, which consent to form a larger union. Thus, individuals owe sovereign allegiance to their state, not the national government. To the extent that the federal government has power, it is granted that power by the permission of the states making up the confederation, and such power can be revoked by any state not extending the federal government such permission.

In the United States prior to the US Civil War, the States Rights movement advocated the idea that the US was really a Confederation. The Civil War definitively settled this issue: the US is legally a Federation.

Post-Civil War, the States Rights' movement has adopted a less absolute position, in that while they recognize the Federal Government as absolute (and that the US is indeed a Federation), they advocate that significant powers were strictly delegated to the states by the US Constitution (which is the document that defines the limits of the US government's powers). In particular, while recognizing Article VI (supremacy of the Federal government), they advocate that significant laws and regulations undertaken by the Federal government actually violate Article IV (states' powers and rights).