Why was Plessy v. Ferguson such an important case for the South, and what effect did it have on the practice of segregation?

plessy v. ferguson was a supreme court case where Homer Plessy who was 7/8 white and 1/8 African American tried to sit in a whites only car on a train to challenge the segregation act. Plessy was found guilty of violating the segregation Act and supreme court said that the state law was constitutional and that the segregation did not imply inferiority of African Americans. Ferguson was the respondent.