Banneker questioned Jefferson's action on slavery because Thomas Jefferson wrote about equality of all being in the constitution of America, but he himself made a contradiction to his statement by restraining slaves under severe persecution.
In 1791, when the "Bill of Rights" took the authority, the opportunities this Bill of the Rights granted were kept away from thousands of Africans living in America under the institution of Slavery. Hence, Benjamin Banneker ( a free African-American) questioned the way by which the Whites regarded and treated the Blacks in the United States. He pointed out the inconsistencies between the policies laid out in the Bill of Rights and the existence of slavery.
