An abolitionist who received an honorary degree from Amherst in the same ceremony as Charles Sumner, he became a Republican and was reelected to Congress as such in 1856.

There is speculation [2] that Chaffee advanced the Dred Scott case as a test for slavery.

However, contemporary reports have him discover from the Springfield Argus that his new wife owned the most famous slave in the world in February 1857, only a month before the Supreme Court handed down the infamous Dred Scott decision.

Criticized nationwide for apparent hypocrisy, Chaffee immediately arranged for the return of Scott to his original owners, the Blow family, for emancipation.

Because of negative publicity from the Scott case, Chaffee did not seek reelection in 1858 and became Librarian of the House of Representatives from 1860-1862.