The Fugitive Slave Act of 1850, just like the Nullification Crisis, was created in an atmosphere defined by North/South animosities and questions about the nature of federal power. But as if it was in some sort of bizarro United States, the the South wanted stronger federal control and the nullies lived in the North.

Slaveholders owned slaves as property—very expensive property—and when any of them escaped, slavers wanted them back. And who did the government-hating, states' rights loving Southerners turn to? The federal government. As U.S. territory expanded, a compromise was made in Congress. Basically, an agreement was reached where slavery would not expand into new states, but also that the south could enforce even stricter rules on their own slaves.

This became known as the Compromise of 1850, and the Fugitive Slave Act was part of it. It forced runaway slaves to be returned to their master. Even if they made it all the way to Maine, they had to be returned.

But here's the kicker. States like Wisconsin and Vermont began nullifying the act, saying it was unconstitutional. Now, the nullies began arguing for the North and refused to enforce the law. Ultimately, this situation never got resolved since relations between the North and South went downhill from there. Can you say "ironic twist of events" Can you also say, "History repeats itself"?