White Southerners certainly weren’t states’ rights doctrinaires. They were perfectly fine with an aggressive federal government if it worked to preserve slavery. They had no objection when Congress passed the Fugitive Slave Act of 1850, requiring free states to aid in the return of runaway slaves — overriding many of those states’ own laws. When South Carolina issued its secession ordinance in 1860, it even complained that Northern states had passed laws nullifying the Fugitive Slave Act; complained, in other words, that Northern states were refusing to obey the federal government! It was only when the federal government threatened the institution of slavery that the Southern elite invoked states’ rights.
— William Black, in this article