The important role of the U.S. Supreme Court in defining civil liberties in the 20th century can be seen through landmark cases that established precedents for individual rights. Through interpretation of the Constitution, the Court addressed issues such as free speech, privacy, and due process. Notable cases like Brown v. Board of Education ended racial segregation in public schools, while Roe v. Wade affirmed women's rights to make medical decisions. The Court's rulings shaped the social and political landscape, often reflecting evolving societal values. By affirming or protecting civil liberties, the Supreme Court has played a crucial role in advancing social justice and individual rights in America.