What light does Northup's account shed on the biblical arguments that were traditionally used to justify the institution of slavery (refer to document 70 here if you need more information) ?

Salomon Northup was an African American abolitionist who lived throughout the first half of the 19th century. He was a born as a free man. He is known for being the author of the book "Twelve Years as a Slave", which tells the history of his life during the years he was kidnapped and turned into a slave.

One of the biblical texts which Christians at the time used to justify slavery was Genesis IX, 18-27 which describes the exile of Ham during the events of "Noah's Arc". The belief is that Ham was then turned black and all of his descendants were made Africans.