During the conflict between nationalists and states' rights advocates, the idea of nullification developed. what was the central principle of nullification?

The principle of nullification is based on the theory that a state has the right to nullify, which means invalidate, any federal law that it seems unconstitutional, as people thought that a tools should existed in order to avoid the risk of pass an unconstitutional law. In practice, the principle should be executed by challenging the Supremacy Clause where states challenge the federal government by nullifying federal law.