The document that established the principles of democratic governance in the U.S. is the Constitution, drafted in 1787 and ratified in 1788. It created a framework for the federal government, delineating the separation of powers among the legislative, executive, and judicial branches. The Constitution also includes the Bill of Rights, which guarantees fundamental individual liberties. This foundational document has served as a model for other democracies worldwide, reinforcing key democratic principles like rule of law, checks and balances, and citizen participation in governance through elected representatives.