The crucial document for understanding civil rights in the United States is the Bill of Rights, the first ten amendments to the U.S. Constitution. Ratified in 1791, it guarantees fundamental freedoms, such as freedom of speech, religion, and the press, as well as protections against unlawful searches and seizures, self-incrimination, and cruel punishment. The Bill of Rights has served as a foundation for many landmark Supreme Court decisions regarding individual rights, shaping the legal framework for protecting citizens from government overreach throughout U.S. history.