The Brown v. Board of Education decision overturned the previous "separate but equal" legal doctrine established by the Plessy v. Ferguson decision. The Brown v. Board of Education decision declared that segregation in public schools was unconstitutional and violated the Equal Protection Clause of the 14th Amendment of the U.S. Constitution. This decision marked a significant turning point in the Civil Rights Movement and paved the way for further legal challenges to segregation and discrimination in all areas of American society.