"During the Constitutional Convention of 1787, the pro-slavery members, who eventually became the Democratic Party five years later, argued that slaves should be counted as citizens when considering the number of congressional seats their state would receive. They made this argument even though they had no intentions of giving the slaves the same rights afforded to the white citizens of their states. The anti-slavery members, who eventually became the Republican Party, strongly opposed this racist proposal. To finalize the constitution and not give in totally to the pro-slavery members, they reached a compromise with a three-fifths clause. Under the new clause, the pro-slavery states could only count the slaves three-fifths of a person when determining how many congressional seats their state would receive. Shortly after this matter was settled, Pierce Butler, a representative from the slave state of South Carolina argued that the document should include a Fugitive Slave Clause. Under his proposed recommendation, runaway slaves would be classified as criminals and treated as such. To avoid any further delays in finalizing the constitution, the constitutional convention approved the clause but stated the federal government would not enforce this clause, enforcement would be the responsibility of the individual slave state."
January 1, 1970
https://en.wikiquote.org/wiki/United_States_Constitution