From The Washington Examiner:

In linking it to slavery, he wrote, “A sad irony is that the ‘sanctuary’ movement conjures the disturbing nullification movements of the past three centuries in Virginia. Thomas Jefferson and James Madison argued that the states have the right to ignore federal laws they consider unconstitutional. That thinking was applied to proslavery movements, leading to the Civil War and the fight over integration in the 1950s and 1960s.”