The Saint Louis Cardinals organization, which has several hundred employees, recently went through a round of hiring. During the round of hiring, the Cardinals organization told all prospective job applicants that they have to join a specific union to even apply for a position with the Cardinals organization. Several die-hard baseball fans wanted to work for the Cardinals organization but were opposed to the idea of joining a union. The individuals applied anyway, were interviewed, and told the Cardinals organization they refused to join the union during the interview. The Cardinals organization refused to consider hiring these individuals because the individuals refused to join the union. The Cardinals organization did not cite any other reason for not hiring the individuals aside from their refusal to join the union. Explain whether the union violated any labor laws?