The "supreme law" of the United States is the Constitution, which outlines the country's national government and laws. It also guarantees basic rights for its citizens.
The U.S. Constitution was signed on September 17, 1787. It outlined a plan for a stronger government structure, which included three branches and a system of checks and balances to limit power to any single branch. In 1791, the Bill of Rights was ratified by Congress and it became part of the Constitution. These included 10 amendments that guaranteed basic individual rights, such as the right to the freedom of religion, right to vote and the right to freedom of speech.