The Act prohibited further importation of slaves into the state, required Pennsylvania slaveholders to annually register their slaves (with forfeiture for noncompliance, and manumission for the enslaved), and established that all children born in Pennsylvania were free persons regardless of the condition or race of their parents.
Those enslaved in Pennsylvania before the 1780 law entered effect remained enslaved for life. Another act of the Pennsylvania legislature freed them in 1847. Pennsylvania's "gradual abolition"—rather than Massachusetts's 1783 "instant abolition"—became a model for freeing slaves in other Northern states.
1780 Amendment
The 1780 Act prohibited further importation of slaves into Pennsylvania, but it also respected the property rights of Pennsylvania slaveholders by not freeing slaves already held in the state. It changed the legal status of future children born to enslaved Pennsylvania mothers from "slave" to "indentured servant", but required those children to work for the mother's master until age 28. To verify that no additional slaves were imported, the Act created a registry of all slaves in the state. Slaveholders who failed to register their slaves annually, or who did it improperly, lost their slaves to manumission.
The 1780 Act specifically exempted members of the U.S. Congress and their personal slaves. Congress was then the only branch of the federal government under the Articles of Confederation, and met in Philadelphia.
1788 Amendment
An Amendment, created to explain and to close loopholes in the 1780 Act, was passed in the Pennsylvania legislature on 29 March 1788. The Amendment prohibited a Pennsylvania slaveholder from transporting a pregnant enslaved woman out-of-state so her child would be born enslaved; and from separating husbands from wives, and children from parents. It required a Pennsylvania slaveholder to register within six months the birth of a child to an enslaved mother. It prohibited all Pennsylvanians from participating in, building or equipping ships for, or providing material support to the slave trade.
The 1780 Act had also allowed a non-resident slaveholder visiting Pennsylvania to hold slaves in the state for up to six months. If those slaves resided any longer than six months they automatically became freemen. But a loophole was soon identified and exploited: if the non-resident slaveholder took his slaves out of Pennsylvania before the 6-month deadline, it would void his slaves' residency. The 1788 Amendment prohibited this rotation of slaves in and out-of-state to subvert Pennsylvania law.
The 1780 Act had exempted personal slaves owned by members of Congress. But by 1790, when Philadelphia became the temporary national capital for a 10-year period, there were three branches of the federal government under the U.S. Constitution. There was confusion about whether or not the Pennsylvania law extended to all federal officials; members of Congress (legislative branch) remained exempt, but there was uncertainty regarding whether justices of the U.S. Supreme Court (judicial branch) and the President of the United States and his Cabinet (executive branch) would also be exempt. Attorney General Edmund Randolph lost his personal slaves to manumission due to his misunderstanding of the state law. He conveyed his advice to President George Washington through the president's secretary, Tobias Lear:
"This being the case, the Attorney General conceived, that after six months residence, your slaves would be upon no better footing than his. But he observed, that if, before the expiration of six months, they could, upon any pretense whatever, be carried or sent out of the State, but for a single day, a new era would commence on their return, from whence the six months must be dated for it requires an entire six months for them to claim that right."
Washington argued (privately) that his presence in Philadelphia was solely a consequence of the city being the temporary national capital, and that he remained a citizen of Virginia and subject to its laws on slavery. Still, he himself was careful not to spend six continuous months in Pennsylvania, which might be interpreted as establishing legal residency. Had he litigated the issue, it might have clarified his legal status and that of other slaveholding federal officials. But it also would have called attention to his slaveholding in the President's House, and put him at risk of losing those slaves to manumission. It was thought that he followed his Attorney General's advice, and knowingly and repeatedly violated the state's 1788 Amendment by rotating the enslaved Africans in his presidential household in and out of Pennsylvania. There is no record of Washington having been challenged for this. According to Lear, the Pennsylvania Abolition Societyseems to have turned a blind eye to the President's actions:
That the Society in this city for the abolition of slavery, had determined to give no advice and take no measures for liberating those Slaves which belonged to the Officers of the general Government or members of Congress. But notwithstanding this, there were not wanting persons who would not only give them (the Slaves) advise, but would use all means to entice them from their masters.
I think he deferred to the state as a courtesy, not a necessity.