The historical document that established the principle of checks and balances in the U.S. government is the U.S. Constitution, ratified in 1788. The Constitution created a federal government with three branches: the legislative, executive, and judicial. Each branch has specific powers and responsibilities, along with mechanisms to limit the powers of the others. This framework was designed to prevent any single branch from becoming too powerful, promoting accountability and accountability within the government. The system of checks and balances is fundamental to the U.S. political system, influencing governance and protecting citizens' rights.