What was Jefferson’s reasoning in the Kentucky and Virginia Resolves?

Jefferson and Madison's Kentucky and Virginia Resolutions (political statements), which were drafted in 1798 and 1799, by the Kentucky and Virginia legislatures took the position that the federal Alien and Sedition Acts were unconstitutional. The resolutions argued that the states had the right and the duty to declare unconstitutional any acts of Congress that were not authorized by the Constitution. In doing so, they argued for states' rights and strict constructionism of the Constitution. The Kentucky and Virginia Resolutions of 1798 were written secretly by Vice President Thomas Jefferson and James Madison, respectively.