The historical document that laid the foundation for civil rights in the U.S. is the Constitution, particularly the Bill of Rights, which was ratified in 1791. The Bill of Rights comprises the first ten amendments to the Constitution and guarantees essential freedoms, such as freedom of speech, religion, assembly, and the press, as well as protections against unwarranted government intrusion. Over time, these amendments have been interpreted by the Supreme Court to expand civil rights further, serving as a critical framework for future civil rights movements. The Constitution remains a living document, continually shaping the evolving understanding of individual liberties in America.