Which of the Supreme Court rulings denied black Americans their Civil Rights?

Not sure what lesson you speak of but in 1955 Brown vs The board of education the supreme court held that the school systems must abolished racial dual systems there for now you have a clasroom with children of diferent colors and from diferent nationalities. Also this is also related to the Little Rock 9 on which the president sent the 101st airborne division of the united states army and also federalized the arakansas 10k national guard troops. The president did this in order to force integration and upheld the supreme court ruling.

Thats just one...