Marbury was a president. At the end of his term, he appointed 16 justices, Madison was the secretary whose job it was to explain the work of the 16 justices, but Madison did not. So Marbury and 16 justices sued Madison. Marshall, who was then the judge in the case, observed that the Act by which they filed the case was unconstitutional. so, the case was dismissed. Because we know that if any law is inconsistency with constitution it will be void