How did frederick douglass use the declaration of independence to argue against slavery

Douglass drew on the custom of natural law in his argument against slavery. The past of Western equality and political belief places a strong importance on fairness and social development, which Douglass contended must have successively prejudiced the general ideas of America’s founding documents. According to Douglass, slavery also opposed the formation story of the Christian Bible, which states God "hath made of one blood all lands of men for to live on all the face of the earth." According to Douglass, the Bible’s assertion of worldwide brotherhood, produced it to become a natural law that would have affected the framers' conscripting of the Constitution.