Personal liberty laws, passed in the late eighteenth century through the 1850s, challenged the implementation and undermined the legitimacy of the 1793 Fugitive Slave Act and related constitutional clause.

Southern states claimed that the new laws were unconstitutional and ultimately used them as part of the rationalization for secession and forming the Confederacy. “Personal liberty” referred to the rights of formerly enslaved persons to retain the free status that took effect when they reached a state or territory that did not allow slavery. It served to block agents of slaveholders from capturing formerly enslaved persons, even those who had escaped bondage and whose former owners did not recognize their freedom. Such acts of “capture” were legally recognized as kidnapping.

These laws were significant in the fundamental differences between Northern states, in which slavery had been abolished, and Southern states, where it remained legal. Southerners claimed that owners had the right to pursue and capture the African American people they considered their property, even if such pursuit took them across the boundaries into free states. Having drastically different laws made the Northern states a safe haven for those fleeing enslavement, which caused resentment among Southern slaveholders concerned about the economic burden and loss of power.