Which resolutions argued that states could nullify federal laws they found unconstitutional?

The Kentucky and Virginia Resolutions were significant political statements crafted in the late 18th century by Thomas Jefferson and James Madison, respectively. They were a response to the Alien and Sedition Acts of 1798, which many saw as an overreach of federal power. The resolutions articulated the idea that states had the authority to nullify federal laws that they believed violated the Constitution. This principle of states' rights asserted that if the federal government enacted laws that were deemed unconstitutional, states could refuse to enforce those laws within their borders. This concept would resurface in later political struggles, particularly in the context of the Civil War and issues surrounding slavery.

In contrast, the Missouri Compromise, the Hartford Convention, and the Compromise of 1850 dealt with various political and sectional issues, such as territorial expansion, the balance of power between free and slave states, and the governance of territories, but did not advocate for the ability of states to nullify federal laws on constitutional grounds. The focus of those events was more on compromise and sectional tensions rather than constitutional authority regarding state rights against federal law.