Even though our Federal government functions as three co-equal branches: the legislative, the judiciary, and the executive; the only unelected branch, the judiciary, defines the meaning of the Constitution. The role of Chief Justice John Marshall in making it possible for the U.S. Supreme Court to become the ultimate interpreter of the Constitution is discussed in detail, with particular emphasis on his opinion in Marbury v. Madison. Other important challenges to the Court's assertion that it alone should define the Constitution are also discussed, as is the Court's role in establishing constitutional doctrines and their acceptance. The Court's 1954 decision in Brown v. Board of Education invalidated racial segregation in public education, thus paving the way for making all forms of public racial discrimination invalid under the Constitution. Public acceptance and support of the Court's role is fragile, something that those who would have the Court move very fast or too slowly on certain issues should remember. 17 footnotes.