On March 11, 1861, seven former US states adopted the Constitution of the Confederate States of America, which closely followed the language, if not necessarily the purport, of the original US Constitution.
Section 9 (4) of the Confederate Constitution read “No bill of attainder, ex post facto law, or law denying or impairing the right of property in negro slaves shall be passed,” enshrining the right to own slaves as fundamental law.