Who wrote the Bill of Rights?

The Bill of Rights was written by James Madison. Madison argued in the Federalist Papers that the Constitution itself was a strong enough guarantor of the people's rights. Anti-Federalist delegates to the Constitutional Convention stated that they would only vote to ratify on condition that the Bill was included.

Madison drew heavily from the Virginia Declaration of Rights, written by George Mason and ratified by the state in 1776. The Bill of Rights restricted the powers of the federal government, but it was not applied to state governments until the passage of the 14th amendment. This practice is called "incorporation" in jurisprudence.