Most students study Dred Scott v. Sandford (1857), but few students are familiar with Prigg v. Pennsylvania (1842). This case considered the constitutionality of the Fugitive Slave Act, which Congress enacted in 1793. It authorized slave catchers to travel across state lines and arrest runaway slaves. This federal law was very unpopular in northern states that opposed slavery. Pennsylvania and other abolitionist states enacted so-called personal liberty laws. These laws prevented a person from being removed from the state without a full judicial proceeding—including a jury trial—to determine whether or not that per- son was in fact a fugitive slave. These state laws conflicted with the federal act, which afforded only minimal procedural protections to alleged runaway slaves. In Prigg v. Pennsylvania, the Supreme Court found that the federal law was constitutional and superseded, or preempted, any state laws to the contrary.
At this time, Maryland was a slave state, and Pennsylvania was a free state. In 1832, Margaret Morgan, a slave, left Maryland to marry a free black man in Pennsylvania. (She apparently did so with the acquiescence of her owner, John Ashmore.)