Civil liberties are fundamental rights that protect individuals from government overreach. These include freedoms of speech, religion, and assembly, as well as due process rights. They serve as a crucial check on government power, evolving through judicial interpretation and societal changes. The U.S. Constitution, particularly the Bill of Rights and 14th Amendment, safeguards civil liberties. Key Supreme Court cases have expanded their scope, while ongoing debates address issues like privacy, hate speech, and religious accommodation in a changing world.