Explain how Jim Crow laws circumvented the intent and meaning of the Thirteenth, Fourteenth, and Fifteenth Amendments

The main way in which Jim Crow laws circumvented the intent and meaning of the Thirteenth, Fourteenth, and Fifteenth Amendments (the Reconstruction Amendments) is that they made it difficult for blacks to do things like vote and engage in standard civic behavior, which reduced them to being less than citizens.