Explain why the supreme court's decision in plessy v. Ferguson was unconstitutional?

Plessy v. Ferguson was unconstitutional because it legalised segregation.

Explanation:

Plessy vs. Ferguson was important supreme court case in which the court ruled that if the separate services offered to the blacks is equal to the ones provided to the white Americans then it doesn't violates the constitution, It couldn't be considered as a violation of the constitution. This ruling sanctioned the Jim Crows Laws that prevented the African Americans from sharing public facilities. It was unconstitutional because it allowed the segregation.

While in Brown v. Board of Education (1954) it ruled that the segregation in public schools was unconstitutional even if the segregated schools were on par with the white schools. The court upheld that segregation violated the 14th amendment.