It was not until well into the 20th century that 14th Amendment jurisprudence would deviate from its earlier interpretations (sometimes known as the Lochner era of the 14th Amendment). In his years as an attorney with the NAACP, Thurgood Marshall played a key role in this change with many civil rights victories. His best known achievement, his victory before the U.S. Supreme Court in Brown v. Board of Education in 1954, relied on the 14th Amendment to strike down the “separate but equal” doctrine established by Plessy v. Ferguson. When Marshall joined the U.S. Supreme Court in 1967, he continued to be a strong advocate for an expansive interpretation of the 14th Amendment.