In Supremo Apostolatus

In Supremo Apostolatus is a papal bull issued by Pope Gregory XVI regarding the institution of slavery. Issued on December 3, 1839 as a result of a broad consultation among the College of Cardinals, the bull resoundingly denounces both the slave trade and the continuance of the institution of slavery.

Effects in the United States
The Bull was not well received among slave holding Catholics in Maryland which was the center of American Catholic population and governance until the late 19th Century. To avoid penalties from Rome while still supporting the status quo, American Catholic clergy often interpreted the bull as denunciation of the slave trade but not as a denunciation of the institution of slavery itself. To avoid apparent contradiction with Rome, the Catholic bishops in America remained publicly silent on the issue.