The event that led to the establishment of the U.S. Bill of Rights in 1791 was the ratification of the U.S. Constitution. During the debates surrounding the Constitution's ratification in 1787-1788, many states expressed concerns about the lack of explicit protections for individual rights. To address these worries and secure broader support for the Constitution, the Federalists promised to add a Bill of Rights. Thus, in 1789, James Madison introduced a series of amendments, ultimately leading to the ratification of the first ten amendments—the Bill of Rights—in 1791. These amendments ensured fundamental liberties, such as freedom of speech and religion.