Bill of Rights
A faction of the men at the Constitutional Convention believed the government document needed to explicitly include rights protecting individuals from a too powerful government. Jefferson led this group called the Anti-Federalists and argued the elite and a central government could not be trusted without adding rights that would protect individuals and the state from a tyranny.
The Constitution was ratified under the condition that a Bill of Rights would be added and ratified shortly after. The Bill of Rights is the first ten amendments to the Constitution and provide explicit rights protecting individuals.