It was not long after the federal Constitution was created in 1787 that many antislavery Northerners began labelling it a pro-slavery document. Parts of it did support slavery — the clause that counted a slave as three-fifths of a person, which gave the slave states greater representation in Congress and the Electoral College than opponents of slavery believed they deserved; and the fugitive slave clause, which required persons held to service who had escaped to free states to be returned to their owners.
We have long known of this pro-slavery view of the Constitution, one that has been much emphasised