 He established a private legal practice in Baltimore before founding the NAACP Legal Defense and Educational Fund, where he served as executive director.In that position, he argued several cases before the Supreme Court, including "Smith v. Allwright", "Shelley v. Kraemer", and "Brown v. Board of Education", the latter of which held that racial segregation in public education is a violation of the Equal Protection Clause.In 1961, President John F. Kennedy appointed Marshall to the United States Court of Appeals for the Second Circuit.