What is the purpose of the equal protection clause? What did Plessy v. Ferguson and Brown v. Board of Education say? What are two ways of understanding the clause? This video lecture is part of an online course taught by University of Pennsylvania law professor Kermit Roosevelt III. “Introduction to Key Constitutional Concepts and Supreme Court Cases” covers the topics: Where does the Constitution come from? How has it changed over the years? How do we know what it means?