The U.S. Supreme Court has long withstood different periods characterized as originalist and living constitutionalist majority rule, which has helped define America not only through law precedents but the ideas they contained. Former Supreme Court Associate Justice William J. Brennan Jr. heavily influenced the future of progressivism in America through his belief in living constitutionalism through the Fourteenth Amendment, which helped define liberalism and correct social injustices. This research analyzes Brennan’s opinions concerning important and lasting cases involving the Fourteenth Amendment such as the Regents of the University of California v. Bakke, Plyler v. Doe, Near v. Minnesota, and New York Times Company v. Sullivan and how they have defined living constitutionalism and the First Amendment. These influential cases explore how Brennan’s influence helped define the Court and progressivism concerning historical wrongdoings.