Conduct some research and identify the only legal monopoly. Why the court decided as they did?

In 1890 the United States had major concerns about the market structure monopoly and its impact of consumers and the economy. The Sherman Anti-Trust act was passed and has been the standard since to prevent monopolies. In 1922 the Supreme Court heard a case brought by a competitor against a major business entity and ruled that this business was exempt from anti-trust legislation. It has continued exempt for close to a hundred years. Conduct some research and identify the only legal monopoly. Tell us who they are? Why the court decided as they did? Add your opinion – should that exemption continue today? Why or Why Not?