The Fugitive Slave Act controversy was, at bottom, a battle over slavery. But like today’s fight over immigration enforcement, it took the form of a dispute about constitutional rights and civil-court jurisdiction—and beneath it, then as now, about citizenship, about who belonged to the national community and who was without rights. Its roots lay in the bargain between South and North that made the Constitution possible (the agreement that William Lloyd Garrison, the abolitionist, later called “a covenant with death and an agreement with hell”). Article IV, Section 2, Clause 3 required that “No person held to service or labour”—a euphemism for slavery—” in one state” could change their status by escaping to another state; escaped slaves were to be “delivered up on claim of the party to whom such Service or labour may be due.” It was an essential guarantee for enslavers and what came to be known as Slave States, but it left questions, which became bitter disagreements as the Northern states gradually abolished slavery, and Northern people came to fear and despise the South’s “peculiar institution.” Who was responsible for “delivering” escaped slaves? What were the constitutional obligations of a free state where an escapee found refuge? How could a slave “owner” go into a state where slavery had no legal existence and establish that “service or labour” was “due”?
Under the Fugitive Slave Act of 1793, an enslaver who tracked down an escaped slave could—often assisted by bounty hunters—seize the escapee and drag them before any judge or magistrate. If they provided evidence of “ownership,” the judge was to issue a warrant to return the slave to the place of bondage. But as the 18th Century wore into the 19th, Northern revulsion at slavery and the brutal tactics of slave catchers produced a reaction against Free State involvement in slave rendition. Some states passed “personal liberty laws,” which forbade state officials to aid in returning alleged slaves to bondage and guaranteed anyone seized as a fugitive slave would be entitled to habeas corpus and a jury trial to establish their legal status. The pro-slavery Supreme Court struck down these laws. Still, resistance persisted. The South, by 1850, threatened secession if it did not get effectual guarantees that fugitives would be returned without a lot of messy rights or complicated procedures.
The result was the so-called Compromise of 1850, which included an even more draconian Fugitive Slave Act. It set up a parallel federal court system of commissioners to empower slave catchers to take alleged fugitives south. (The commissioners received $10 for every rendition they approved but only $5 for cases in which they ruled for the alleged slave). Accused fugitives would have no access to habeas corpus and no right to trial by jury. Resistance to slave rendition by anyone was made a federal crime; slave catchers were empowered to conscript civilians on the spot as slave-catchers.