Let's see now. In the United States of America from 1776 to 1868, slavery was the law of the land. That's 92 years you need to excuse our government. But only if you are human scum.
Slavery as practiced in 1860 was significantly more harsh that that practiced during the American Revolution, and—even though it was deleted to appease the Southern colonies—Thomas Jefferson—a slave owner—included language in the draft of the Declaration of Independence which specifically decried slavery.
I guess his services wouldn't have been needed in 1860's Virginia when the pro-slavery elites decided to "improve" on the original United States Constitution.
Granting that it was ignorant and hypocritical to practice slavery in the Revolutionary period, it was even more so by the time almost another century had passed...