Answer:
Plessy v. Ferguson was a Supreme Court ruling relating to a Lousiana law in 1896.
Summary
Plessy v. Ferguson was best known for creating the ruling "separate but equal." Lousiana law created "whites only cars" for trains. This was after the 14th amendment, which stated all citizens had equal protection under the law. So, the court had to decide if segregation was constitutional under the 14th amendment.
Problematic Ruling
The Justices in the supreme court decided that segregation was still legal. The idea was if the separate cars, or other areas, were equal, then no laws were being broken. However, it was extremely uncommon for areas created for black people to be equal to white areas.
This meant that it was rare for areas and services to truly be "separate but equal." So, the ruling was problematic because segregation was not equal and specifically made to be racist.